Breakfast the next morning was more tense than usual. For one thing, Rose was far more alert than she'd ever been in the morning, watching him with bright, inquisitive eyes, and the Doctor knew that she hadn't forgotten their truncated conversation of the previous night and was simply waiting for him to bring it up again. The Doctor, for his part, was trying to stay on top of his nerves as he prepared himself to undertake what would potentially be the most important conversation of their relationship.

As they were sitting across from each other nursing their second cup of tea, Rose finally took the initiative. The Doctor was surprised it had taken her so long.

"All right, Doctor," she said, not unkindly, leaning back slightly in her chair. "How'd you like to do this?"

He swallowed the sense of irrational panic that threatened to choke him, gathering up enough air to speak. "Well…" His voice emerged several octaves higher and he cleared his throat again, as Rose watched with a fond expression on her face. "For starters, I'd really like to go to the med bay and run some tests." He saw her expression fall as he said the hated 'm' word and hastened to explain.

"Please, Rose. We already know you've changed. I need to know how, and how much." He hoped she knew he wasn't trying to dodge the discussion and quickly added, "we can talk while we're there, Rose, I promise. But it would honestly help me give my explanation if I knew… well, what to explain."

Rose was already halfway to her feet. "I guess I should just be surprised it's taken you two days to ask - I'm actually sort of impressed, Doctor."

He scratched the back of his neck ruefully, conceding the point. His restraint had been deliberate, and difficult. "I just want to make sure you're safe." I want you safe.

Rose stepped around the table to cup his cheek in her hand. "I know. My Doctor." He leaned into her caress and she placed a soft kiss on his lips before taking his hand.

"Come on, then," she said. "Let's get this over with." He squeezed her hand in relief and followed her to the med bay.

At first, his attention was devoted to setting up the equipment. He had Rose lie on her back as he ran several passes over her with the sonic, setting it to a different frequency each time. Rose sat up as he inserted the sonic into the machine and set the scans to run, and they both reached for their teacups that they'd brought from the galley. She looked at him expectantly, eyebrow arched, and he realised he was no closer to a beginning than he had been the previous night.

"So… telepathy," she prompted. The Doctor nodded vigorously, and opened his mouth once or twice to say something, only nothing came out. She shook her head indulgently, taking pity on him.

"Let's start with what the rules are, Doctor. I know you said I didn't do anything wrong but you still had to pull back. You said you'd explain why."

Buoyed by the underlying assumption that she intended to repeat the previous night's activities, the Doctor took a fortifying sip of his tea. That was his Rose. Always cutting straight to the heart of the matter. Rules. He could work with rules.

"Well, the rules are different for each telepathic species, of course," he began, and Rose gave him a look that told him she knew what he was doing and he quickly put himself on track. "But for my people - Gallifreyans - it all boils down to a few central tenets. Consent, obviously, is paramount, which you already know. Respecting privacy, locked doors, all that."

He paused. Most of the regulations actually involved bonded pairs rather than general telepathic contact, and he still hadn't thought of a way to bring that up.

"So touching while in each other's minds is…" Rose prompted again, a touch impatiently (as well she might), and the Doctor took a deep breath.

"It's fine in theory," he said at last. "Of course, Gallifreyans in general and Time Lords in particular weren't much given to contact in any form, physical or otherwise: exchange of emotions was thought to be quite sufficient. However, given the heightened emotions inherent in any telepathic exchange, it's easy for matters to… escalate. Especially between two people who love each other." He used the word deliberately and his reward was the smile that broke across Rose's face like the dawn.

"You mean, like telepathic sex?" she asked, not looking daunted in the slightest by the prospect, and the Doctor was forced to confront a whole other set of difficulties for this conversation that he hadn't considered. He swallowed thickly, tasting the tea in the back of his throat.

"Yup!" His voice was squeaky again and he worked to force it back to its usual tenor. As he'd expected, he was having a hard time disguising how much he wanted this. Rose looked speculative, and it was all he could do not to throw himself at her and beg her to let him show her what it could be like. He had Plans. Would have plans. Anyway.

"So you pulled back last night because you didn't want to…" She bit her lip in an uncertain expression, and the Doctor nearly sent his cup of tea hurtling to the floor in his haste to take her hands, twining them in her lap.

"I meant what I said last night, Rose. It was incredible. I wanted…" His voice cut out under the weight of just how much he wanted, and from the sudden widening of her eyes, it seemed Rose understood. The presence of her hands in his kept him from clenching his fists. "But I couldn't. Not until you understood everything that would entail."

She nodded slowly. "Consent, yeah." He felt an odd sense of relief that she was taking this so seriously, although he hadn't really expected otherwise. It was time.

"I told you already, that my people preferred to experience emotional rather than physical contact - speaking of ordinary Gallifreyans, of course, very little emotional exchange going on amongst us Time Lords - well, it was the same for intimacy. Given our long life spans the urge to procreate was not a priority, so over time we evolved to require only the mental aspect."

A spark of realisation lit in Rose's eyes and he knew she'd already put together what that meant for him without him even needing to put it into words. His love for her soared even as he hastened to reassure her.

"Now, obviously that's not the case for me. Even if I weren't now affected by a certain biological imperative-" one that had wasted no time in kicking him upside the head when he was presented with the vision that was Rose in her Cardiff gown, catching him completely off guard - "I've always felt very differently about you, love."

Rose smiled shyly at him from beneath her luscious lashes, proving his point, and the Doctor had to force himself to continue with the discussion.

"So you want to… with me." Rose said. It wasn't quite a question, but the Doctor responded anyway.

"Oh, yes." As if that could ever have been in doubt. Rose frowned slightly.

"So why couldn't you, Doctor? Why hold back this time? You didn't when…"

Passionate memories of their previous trysts flooded the Doctor's body with warmth and he groaned low in his throat. From the way Rose shifted ever so slightly, recollections were affecting her, too.

"First," he forced out, unwilling to be distracted again, "I wasn't sure how much strain your mental capacity could handle, which is another reason I wanted to run these tests." Rose blinked. He could tell she'd forgotten about the exam - he almost had, himself. "And second, that sort of contact is only possible within a bond." The last few words came out in a rush. Rose blinked again.

"A bond," she repeated. The Doctor held his breath. The room had gone fuzzy around the edges, everything except Rose blurry and indistinct. "So just to be clear here, we're talking about more than just a mind meld, yeah? Don't tell me this is like a 'no sex before marriage' thing… is it?" Her voice raised slightly as she found no denial in his expression. He quirked a smile.

"I know. Terribly old-fashioned, isn't it?" He felt a ramble coming on and was helpless to stop it. "Which was why it was starting to become unpopular, even among ordinary Gallifreyans. Permanently sharing your mind with another, letting yourself be that vulnerable, all for some metaphysical canoodling, it just wasn't seen to be worth it. Not to mention all the pomp and circumstance that began to grow up around it. Honestly, I remember one ceremony-"

"Doctor." Rose stopped him, and he was glad to be stopped, his gob taking him places his mind didn't particularly want to go back to. She looked into his eyes for a moment, making sure she had his full attention before continuing. "Is that even something we could do? Is my telepathy strong enough for that?"

There were so many answers the Doctor could give to that question; he settled for a simple, "Yes."

Rose accepted his answer, considered it. He waited with bated breath. Finally she said, "You said it would be permanent, yeah? So what happens, when I…?"

She didn't have to say it - they both knew what she was referring to. The Doctor suppressed a shudder.

"Well, by all accounts, it would be extremely painful if the bond were to be broken for any reason. You're making the other person's mind a part of your own, so you'd be left with a missing piece." He couldn't keep the bleakness from his voice as he forcibly relived the few seconds when he'd thought Rose was going to fall. Being without her - bond or no bond - would have been unbearable. "But unless I very much miss my guess…"

At that moment, the scanner dinged, and the Doctor and Rose both froze.

As though in a trance, the Doctor slowly reached for his specs, carefully unfolding them and putting them on without looking away from Rose. Rose squeezed his hands.

"Okay, Rose Tyler," he exclaimed, rolling his chair back and turning towards the monitor in the same movement. "Let's see what my magnificent time and space ship has to tell us."

He scanned the list, Rose coming to stand behind him even though she couldn't read the script. She was about to prompt for an explanation when the Doctor clapped a hand to his forehead.

"Oh, stupid Doctor!" Rose jumped, startled.

"What is it?" she asked, her voice slightly sharp. His attitude wasn't the most reassuring.

"Oh, I'm sorry Rose, it's nothing bad. I just compared the readings I just took with the ones I got when I took care of you after Canary Wharf." Rose vaguely remembered him being perturbed by something the last time they'd been in here but she'd been more concerned with wanting to get into bed, feeling his arms around her, and putting the whole bloody day behind her.

"Here, look." He changed the readout to English and put the two scans side by side for her perusal. Even in English there were a lot of words Rose didn't know, but she forged ahead anyway, not wanting to be left behind. "I was getting abnormal levels of something in your body but I couldn't tell what it was. I thought it might be residual Void stuff and I was intending to check it later."

"But if it's not Void stuff, what is it then?"

"It's artron, Rose." The Doctor had his chin in his hand, still studying the charts, but his heels were bouncing excitedly under the table.

"You mean, more than normal, right?" Rose asked. Having just explained the concept to Mickey she knew there was something more to it that had the Doctor excited.

"Way, way more," the Doctor said. "In addition to quite a large amount of huon energy. And given that huon particles destabilise the atomic structure I'd normally be very, very concerned by that, but what it says here is exactly the opposite."

Rose read the line the Doctor was pointing to. "My cells aren't aging?" she summarised.

"You aren't aging, Rose," the Doctor confirmed gently, and for the first time since they'd woken up she couldn't get a read on his emotions. "Well, you are, just very slowly. In fact, you're aging just as slowly as I am."

Rose stared with widened eyes at the Doctor, at the screen, and then back again. It was good news, because it meant she wouldn't have to leave the Doctor on his own. It was just a lot to take in. The fact of her mortality had been a sticking point in their relationship for so long; even once the Doctor had finally conquered his fears and given into his feelings she'd been surprised. Ecstatic, but surprised. She couldn't possibly imagine how it might feel to outlive everyone you loved - now, it seemed, she would find out, but with the Doctor at her side. She could face anything so long as that was true.

Imagining that the Doctor's less than enthusiastic reaction was based on similar thoughts, she attempted to steer the conversation in a safer direction. "So wanna explain what the rest of it says?" she asked. She could read it herself but was hoping to distract him, and it worked.

"Enhanced frontal lobe - that's how you can manage telepathy now, Rose. Enhanced strength-"

"Strength?" Rose repeated, in surprise.

"Yup!" The Doctor popped the 'p', then sobered, turning his chair slightly to face her. "Rose, you shouldn't have been able to hang onto that lever as long as you did."

Without thinking about it, Rose took advantage of his changed position to climb into his lap, the reminder making her want to be as close to him as possible. The Doctor's arms closed instantly around her waist, holding her tightly for a moment and stroking her back, reassuring them both.

Once they'd had a chance to compose themselves, he continued, lulling her with the sensation of his voice resonating in his chest. "The sprains I healed… they were consistent with a much stronger force than the human body is built to withstand." He clutched her closer at the reminder of how close he'd come to losing her.

Rose ran her fingers through the short hair at the back of his neck, searching for a way to divert the topic once again. "So - hang on," she said, genuinely curious. "These are changes from when I was Bad Wolf, right?" The Doctor nodded, pulling back to look at her. "So how comes I never noticed any of this before now? Super strength? Telepathy?"

The Doctor luxuriated under her continued caresses, looking pensive. "That's a good question. I believe your telepathy went unnoticed because it was undirected. It's not like you see in the movies, open to every passing thought. Well, it is for some species I suppose, but Gallifreyans were touch telepaths, which means our telepathy is already somewhat focussed in nature." He pressed his tongue to the back of his teeth and Rose wanted to sweep it into her mouth. She refocussed with difficulty.

"From what I can tell, Bad Wolf changed you to be capable of telepathy so that you were able to direct the TARDIS when you merged, but you don't have any innate telepathy of your own. It likely protected you from the psychograft as well. Last night, you were able to follow me back to my mind but I was still sustaining the contact largely on my own. If I had to guess, that is," he added, offhand, but Rose didn't doubt he was right. It was a good enough answer for now.

"So what about the super strength? That's something I'm sure I would've noticed."

"Enhanced strength, Rose, and if you're interested we can test the limits of it later. I doubt you can, say, lift a car or anything like that. But are you so sure you haven't felt the effects of it already?"

Rose frowned, trying to think. "What do you mean?"

"Well, I've never really put it together before now, but that sword you tossed me, when I was fighting the Sycorax?" Rose nodded, remembering. Though she hadn't thought about the incident for some time she considered it one of her finest hours. "Well, that sword was made of halkonite steel: one of the densest metals in the galaxy. And you tossed it, one-handed, what… fifteen, twenty feet?"

Rose blinked. She'd been quite proud of her movie star moment, but had chalked it up to adrenaline when the sword hadn't felt heavy at all in her hand.

"And what about that time on Rysa when we had to escape from those cultists?" The Doctor was starting to sound excited, the way he always was when piecing together a mystery.

Rose's palms grew sweaty at the memory. They'd been herded to take a mountain path that had unceremoniously turned into a sheer cliff face about halfway down. Everything had been going fine until Rose's foot had slipped on a patch of grass and she'd suddenly found herself clinging to the rock face with one hand. She'd managed to switch her grip to a safer part of the cliff in order to descend successfully. In the moment, all she'd cared about was survival, not on precisely how she was able to keep her grip, and afterwards she'd written it off as luck.

"And that's another thing, Rose, now that I think about it. You know I've got a superior physiology; that's just a fact. But you've been keeping up with me much more easily these days. Normally I hold back a little when I'm with someone else but I haven't been, the past little while. I've forgotten to because I haven't needed to." His eyes widened. "Oh."

"What is it, Doctor?" Rose asked again, feeling a little bit like she had whiplash. The Doctor didn't seem too concerned but so much had changed today that she felt slightly off-kilter. To her further confusion, a pink blush appeared high on the Doctor's cheekbones and he shifted under her uneasily, stopping just short of adjusting his collar. His reluctance was obvious, but to his credit he didn't try to evade her question.

"Well, I've just realised what with this talk of your endurance-" here, he seemed to recover some of his aplomb and favoured her with a cheeky wink, leaving her in no doubt about what he meant - "that these changes mean we are far more compatible than I believed at first."

"Oh!" Rose repeated, unable to help the brief panic that flashed through her. She knew it was unnecessary since the Doctor wasn't bothered but she couldn't help it. She'd had a pregnancy scare with Jimmy and it was a feeling you never really forgot.

"Rose?" The Doctor slid his hands up her arms to grasp her shoulders. "It's all right. You're not pregnant. If you were, it would show."

She believed him; he would be far more concerned if there were even the slightest chance. She pushed the irrational fear, which was more memories than anything, aside and nodded at the Doctor.

"It's okay, Doctor. Just a surprise is all."

"I'm sorry, Rose," he said, his expression more concerned now that the discussion was focussed on her. "I told you it was safe, I should've been more certain, I could've…"

Rose shook her head. "You weren't to know," she said, thinking all the while how lucky they'd been. It only took once, and they'd been at least partially compatible the whole time. She couldn't even remember the last time she'd taken birth control. She chuckled a little.

"What is it?" The Doctor's eyes were still searching her expression - he thought she'd be angry with him.

She pressed her lips together briefly, but still answered him, if only because he looked so worried.

"I guess we're not all that compatible then?" She couldn't pin down one thing she was feeling and the Doctor was understandably confused.

"What do you mean?" His eyes widened slightly. "Rose… you don't want children?" It was almost not a question. Rose huffed a breath and shrugged, fighting the urge to pull away from the Doctor, wondering how on Earth she'd ended up in this conversation.

"I dunno, never really thought about it." She tried to keep the defensive edge out of her tone. "I didn't, with Jimmy or Mickey, even if I hadn't been too young, which I was." The Doctor was still watching her intently, and she smiled up at him through her lashes. "And then I fell pretty hard for this fascinating bloke who swept me off my feet to travel through time and space." The Doctor started smiling too, and Rose was relieved when his expression changed. "And since he happened to be an alien, it was never really a consideration for me."

When the Doctor still didn't respond, she blinked, looking at him properly. Beneath the veneer of concern there was longing there, deep and dark and keen. The kind of emotion she had no proper name for, couldn't even begin to grasp with her paltry twenty years of existence.

"Oh," she whispered again. "But you… Doctor, you really want kids." This time there could be no doubt, but he still shook his head immediately.

"Not if you don't want them," he said seriously. He ran a gentle hand through her hair.

"Tell you what," he said, before she had a chance to respond. "We're not deciding this today. I've got a contraceptive I can take in the meantime. If and when you decide you want to revisit this conversation, we can reevaluate. All right?" He carded his hands through the hair behind her ears again, smiling tenderly. "You take as much time as you need."

The breath Rose let out was slightly shaky with relief, and she nodded. "I guess we've got lots of time, don't we?"

The intensity still hadn't left the Doctor's eyes - he looked at her like she was the only woman in the universe. "We do."

The words were an invocation, a vow. She smiled despite the trembling in her chest. "Good."

The corners of his mouth turned down. "Good? Rose, you're going to live a very long time. Maybe even as long as I will. That sort of life… it becomes a burden, after a while."

Rose should have felt angry, but she couldn't stop smiling. She cupped his face in her hands. "Yes, it's good. Because it means you won't be alone, Doctor. I want you safe." His eyes flashed, and his hands twined more securely in her hair. "And that doesn't just mean not in danger. It means your hearts, too." She lowered her hands until they were each resting on top of one.

The Doctor's eyes never left hers. "Rose Tyler."

It reminded her of all the times before he'd said her name as a full sentence, containing more meanings than either of them had words for. It was why she'd never felt like she needed a more overt declaration of his feelings for her: it was all there in those three syllables instead.

They shared a lingering kiss, and when they parted the Doctor was looking at her less like Bad Wolf and more like herself. She knew he was struggling to believe that he deserved what she'd done to herself for him, and yet with her family now living in the parallel world, she didn't feel that it was entirely for his benefit.

"Better with two," she reminded him, and his mouth quirked. "Besides, I'll still have Jack. He'll outlive everyone now, thanks to me." Guilt threatened to overwhelm her, and she pushed it aside with difficulty.

"It's not your fault," the Doctor said quietly, but Rose just inclined her head. Maybe someday she'd be able to believe him. Then his lips turned down again, and her heart sank further when she realised she hadn't distracted him from the previous topic like she'd hoped. "It's not what I would have wanted for you," he said, even more softly, and Rose clenched her hands in his shirt as if to grasp the hearts she hoped to protect.

"Maybe not," she conceded. "But it's what I wanted for you."

The Doctor's eyes widened, and he swooped down to capture her lips again a moment later. Rose allowed herself to get lost in the sensations of kissing the Doctor; kids, super strength, extended life and all of it out the window. If it meant she got to do this, she could handle anything.

Before matters could get too heated, however, the Doctor pulled back. His pupils were blown and his hearts, still under her hands, were pounding, and she realised her declaration had affected him in more ways than one. She blinked up at him as he licked his lips unconsciously, trying to regulate her own breathing. The Doctor cleared his throat.

"So I'll just, ehm, dose myself with this…" He gestured vaguely to a glass cabinet that dominated one of the walls that looked like it contained a vial of every substance ever created - and she wouldn't put it past him if it did.

"And then can we go somewhere else?" Rose begged. "Somewhere with comfy chairs, maybe? I want to talk more about telepathy." Their discussion of bonding had raised far more questions than it had answered before they'd gotten so thoroughly sidetracked. The Doctor's Adam's apple bobbed as he nodded slowly.

"Of course, of course." He found the vial he was looking for and prepared a hypospray. "Now all I have to do is take this every six months and we're safe as houses," he informed her as he worked. "One hundred percent prevention rate." Rose blinked as he gave himself a perfunctory jab in the arm and released the solution.

"There," he said, grinning at her. "All sorted." He paused. "Why do you look so surprised?"

Rose raised one shoulder in a shrug. "It's just… I know in the future medicine's advanced and all but, I dunno, it feels like I should be doing something more about this."

"Oh yes, twenty-first century attitudes towards contraception." The Doctor nodded knowingly as he disposed of the hypospray. "You lot grow out of it, eventually," he drawled, his back to her as he rearranged the scanners, then he turned back towards her, flipping his sonic screwdriver before replacing it in his pocket. "Besides, makes more sense to deal with matters at the source, as it were." He held out his hand to her, waggling his fingers. "Shall we?"

Rose took his hand and followed him out into the corridor. "Where are we going? Library?"

The Doctor shook his head. "It's called the Zero Room."

Rose arched an eyebrow. "Sounds sinister."

"It's not!" The Doctor protested. "It's just… very, very quiet. Cosmically and, more important - at least for our purposes - telepathically so." He slid open a door to an airy, white room floored with a plush carpet. Rose's feet sank into the weave as she felt a wave of peace wash over her, like a headache had been eased that she'd lived with so long she'd forgotten she had it. She let out a long breath, and the Doctor mirrored her at the same moment.

"What is this place?" Rose felt the need to whisper, for some reason.

"This, Rose, is the everything-proof room." The Doctor's voice was quiet and still, but that was more due to the lack of reverberation. "It is the most telepathically neutral space left in the universe and is therefore the best place for you to develop your basic telepathy."

Rose inhaled deeply. "Why does it smell like roses?"

The Doctor pulled her close, burying his nose in her hair. "It always has, since I stole the TARDIS and ran away," he replied. "Her subtle way of hinting me, I suppose. She exists outside of space and time, so in a way you've always been a part of her."

Rose pulled away, grinning up at the ceiling. She almost thought she could hear a hum, like someone listening to a symphony in another room.

"Is that her? Is that the TARDIS?" She looked back at the Doctor, wide-eyed, and found that he was grinning at her.

"That's her. She's expending quite a bit of effort to reach you, but she wanted you to know she was here."

"Hello, Dear," Rose said. The sound caressed her, then it was gone, but the presence lingered.

"Can you talk to her all the time?" she asked, as the Doctor led them to sit in the centre of the room.

"Yup, except when she's sulky and won't talk back," he teased, crossing his legs and resting his elbows on his knees. Rose mirrored his posture. "If we bond, you should be able to too, through my connection." His face shuttered briefly as if he hadn't meant to say that.

"When we bond, Doctor," Rose corrected him gently, and his eyes snapped open. "I want to learn more about telepathy and bonding and everything, but none of it will change my mind. If our life spans aren't going to interfere I want to share forever with you, in every way possible."

The Doctor cupped her face in his hands, his long fingers behind her ears and away from her temples. "Love… I believe you. And I can't tell you just how much that means to me. I may not even be able to fully show you. But you're still so new to telepathy. And there are things in my head that I wouldn't wish on my worst enemy, let alone my third heart."

Rose nuzzled into his touch, feeling a familiar rush of affection for her daft Time Lord. "Doctor, your ship has a room that smells like roses because she knew she would merge with a human so that you wouldn't have to be alone." She met the Doctor's eyes. "I absorbed the Time Vortex so I wouldn't have to leave you. I'm not about to do it now."

The Doctor's expression softened. "Quite right." He pressed a brief, chaste kiss to her lips. "Still, I'm not going to let you agree to anything until you understand more about what telepathy entails. Once we've bonded, there's no going back."

Rose nodded, secretly adoring this honourable streak of his even though she'd never tell him so. "I understand, Doctor," she said, before breaking into a grin. "Just as soon as you admit you're stuck with me."

"Stuck with you, Rose Tyler?" he asked, tracing the shape of her lips with his finger. "Could be worse."

She stuck her tongue out at him and he relented easily, snaking his hand down to her shoulders to pull her closer. "Couldn't be better," he admitted, before connecting their lips again and engaging her tongue in a far more pleasant activity.

Much later, after seeking and being given murmured consent, the Doctor slipped easily into Rose's mind. Now that she knew some of what to expect, the sensation was less overwhelming, but still very pleasant. The Doctor's pearlescent otter swirled in slow patterns in her mind's eye, back and forth.

Hello, she said again, at a loss as to what else to say.

Hello, he responded, no less eager than the first time but his tone was tempered by something else. The pressure seemed more intense this time, as though her submarine had moved to deeper waters, but it could just have been because she was expecting it. Rose, we'll get to the lesson in a minute, but first there's something I want to tell you.

Rose didn't say anything, but she knew the Doctor could pick up on her willingness to listen - she could sense how important whatever he was going to say was to him.

That's right, Rose, the Doctor told her. If she concentrated, she could almost see the otter wearing specs. When our minds are connected like this, we can feel the truth of what the other is thinking. If we were bonded, that's how we would be, all the time. The same way you know how someone close to you is really feeling, even if they've told you otherwise.

Rose considered the Doctor's words. So… you'd always be able to tell what I was thinking? Of course, she'd been able to suss out the Doctor's true feelings for a while now, and vice versa. But she had no point of reference for the degree of intimacy the Doctor was describing.

In a general sense. The Doctor's presence was giving off little sparks in his anxiety. It wouldn't be literal mind reading - not without expending a reasonable amount of effort. But you wouldn't be able to lie, or conceal how you were feeling.

Rose was so surprised she barely even thought about how that would affect her. And… you'd want that. With me. For as long as she'd known him the Doctor had rarely been forthcoming with his feelings.

Yes.

Rose knew what he meant about not being able to lie; there was no question of believing him. But she thought she would have known his sincerity, even if they hadn't been connected. She remembered how it had felt when she was in his mind, that yawning, gnawing emptiness.

Rose… The Doctor paused, and she got confused impressions as he considered. Can we go into my mind for a bit?

Rose couldn't see why not, so she agreed, and without further ado she found herself standing in the console room of the Doctor's creation once again.

Rather than hold himself apart this time, the Doctor came to her and took her hands. More than the usual warmth sparked from the contact, spreading across her skin. Rose felt as though she'd sunk her body into a warm bath.

I wanted to tell you now, before things went any further. Yes, it is empty in my head, emptier than it was ever supposed to be, but that is not why I want a bond with you. That's not why you should agree. I want to be with you, in whatever way you want. The Doctor's eyes, boring into hers, were as dark as she'd ever seen them, fathomless, and yet warmer than the current she could feel running over her skin. That's all I want. All I've ever wanted.

Rose couldn't possibly doubt his sincerity - it loaded his every word and gesture like an anchor. If she'd held any lingering concerns as to his motivations, they were easily dispelled. If anything, she couldn't help but think about the road that had led them here, where his unfinished sentence outside a cafe had become twilit kisses in Churchill's England which had reached their inevitable conclusion beneath an impossible black hole. He'd made the choice to move beyond his very reasonable fears before they'd learned any of this, when he still thought he would lose her at the end of her human life. She'd meant enough to him that he'd moved forward anyway, and her heart swelled to aching with love.

Oh, love… The Doctor pressed a kiss to her forehead that nonetheless felt like the first spark setting tinder ablaze. Rose wondered if she would ever get used to how much more intense feelings were while they were connected.

Indeed… Rose, I believe it would be prudent to move back into your mind now, the Doctor said, his voice sounding strained and his eyes as wild as she'd ever seen them. She could feel the pressure all around her now, squeezing her, but it didn't make her feel uncomfortable; quite the opposite. It felt like a dam before it burst: she wanted to break the restraint and revel in the flood.

Now, Rose, the Doctor reminded her, and reluctantly she led the retreat back into her mind. She couldn't help but feel slightly cold, but it was also somewhat of a relief.

Doctor, how comes we have bodies in your mind but not in mine? She asked a question she'd been considering for a while, watching the silvery beam of light illuminate everything it touched.

We will do, once your telepathy is a little bit more developed, the Doctor answered. He seemed relieved to be in her mind again too, coiling in tight spirals for no overt purpose except because he could. That will come with time. For now, I want to work on the most important thing, which is building up your telepathic barriers. This will keep you safe inside your mind. Aside from preventing less scrupulous telepathic beings from rummaging about inside your head, it will also shield you from incoming signals which could be harmful or overwhelming.

Rose nodded - that sounded very good to her.

I thought it might. Now, I want you to imagine the safest place you know.

Rose couldn't help it - her first thought was of being wrapped in the Doctor's arms.

Rose, please. But the Doctor couldn't hide the flood of emotion that belied his words.

Rose was unrepentant, but she relented, and the Doctor helped her begin to build her own foyer out of her room in the TARDIS.

All right, this will do for now, the Doctor said as he surveyed their handiwork, and Rose felt dual surges of pride, both his and hers. Now you need to focus on making these walls-

Impenetrable? Rose asked.

Not exactly, the Doctor answered, and Rose remembered the first time he'd told her about telepathic contact and thinking that there were layers beyond what he'd explained.

That's right, Rose. Now obviously you want the outer barrier to be as strong as possible because you may not be prepared to assess a telepathic encounter before it begins and you can't be caught off guard. But, remember how you saw my barriers like a castle? Rose saw the portcullis in her mind's eye and could feel the Doctor's pleasure that she was following.

It's a good image to keep in mind. Obviously you want to keep everyone out at first. Then there are people you might want to just allow into your foyer and no farther. For people who are closer to you - friends, family - you might want to let them a little bit further than that. And beyond that…

Bonding, Rose guessed, and the Doctor's presence trembled as he agreed.

Yes. No walls, no barriers. Everything is shared. You become a part of them, and they are a part of you. Always.

It was impossible for him to disguise just how badly he wanted that connection, and his feelings were strong enough that Rose got swept up in them without being able to parse her own reaction. She did want a bond with the Doctor - nothing she'd learned so far had made her want to change her mind. But it was just so new and different from anything that she was used to, she couldn't decide exactly how she felt about it.

That's perfectly fine, Rose, the Doctor told her gently. You've been so incredible about this already. All the changes, not to mention you've clearly got a gift for telepathy. But I want you to learn much more about everything that telepathy entails before you can make an informed decision.

Rose had to admit it seemed like a sensible plan, at which the Doctor preened because of course it was.

Will you teach me how to let you in, no matter what, the way you did with me? Rose asked, and felt the Doctor's love surround her like a candle flame, as well as his simple astonishment that this had been her first concern.

Rose… Of course. If that's what you want. His presence brightened slightly in her mind. But first let's work on getting you some walls so I have something to bypass.

Rose regarded him fondly. You think you're so impressive.

His happiness fizzed through her. I am so impressive! And before we're finished, Rose Tyler, I'm going to prove it to you.

The Doctor was as good as his word. His proclamation heralded a loosely regimented time during which Rose and the Doctor would spend some time in the Zero Room (she could never tell how much - being connected telepathically was like being in a dream, where things she thought had taken forever were instantaneous and vice versa). Afterwards, the TARDIS would send them a restorative tea until Rose felt up to leaving. Then they would read in the library, or watch their favourite movies; something quiet and undemanding, which would allow them to curl up as close as possible.

Rose enjoyed the lessons, and the feeling of closeness with the Doctor it gave her, and she found herself in bed with him at night wondering what it might be like to have that connection all the time. She was making good progress, and was grateful for his care and attention. Mostly the exercises made her feel comfortably sore, like the way she felt after a long workout mixed with the satisfied relief of finally finishing a tough exam. She didn't often require the pills the Doctor had for telepathic pain. Only once, when she took the Doctor's instructions a little too far and ended up trying to block out the TARDIS - impossible anyway, since her connection was what gave her telepathy in the first place - and a second time, when she was experimenting with keeping the Doctor out, to practice rejecting telepathic overtures.

It didn't hurt at first, not like when she'd accidentally blocked the TARDIS, but as the day wore on bringing failure after failure, even the Doctor, who was usually endlessly patient during their sessions, was beginning to feel the pressure.

But I don't want to keep you out! Rose finally snapped, unintentionally breaking their connection and giving herself a headache in the process.

"Rose, I'm sorry," the Doctor said softly. "May I?" He indicated her head.

Rose deliberated for a moment, but she wasn't so daft to turn down his help in a fit of pique, especially since it wasn't really him she was angry at. She nodded as slowly as she could to avoid aggravating her headache, and immediately the Doctor's skillful fingers were working at the base of her skull, alleviating the pressure like he had the first time.

"I'll do better next time," Rose murmured, soothed by his ministrations.

"No, Rose, you're doing so incredibly well," the Doctor said. "The fault is mine, I didn't think… Of course you don't want to keep me out, you told me so before we even began, and I've been forcing you to fight your own mind, which is never a good idea. We'll just have to find you someone else to practice on."

"Who else do we know that's telepathic?" Rose asked, curious.

"I know a few people," the Doctor said lightly. Rose was aware that they were skirting around the issue of how there were no Gallifreyans left to ask. "People I trust enough to allow them near your mind. Not at first, of course, I'd take you to meet them, make sure you felt comfortable. And I'd be right at hand, just in case."

Rose had gotten better at picking up on subtle nuances in the Doctor's voice since spending so much time connected to him, and the subtle edge of danger in his last words made her shiver. She thought of the overwhelming pressure of his full presence that he was constantly holding back from her, and knew that if anyone tried to harm her, they would be obliterated instantly.

They retreated to bed early that night, but didn't sleep until much later. Lying in the afterglow of their lovemaking, in the circle of the Doctor's arms, Rose knew she was the safest she'd ever been. The Doctor might scoff, but when she was close to him, being surrounded by him, either physically or mentally, she knew nothing could harm her.

Through her lessons, all she'd been able to think about was how amazing it would be to be able to feel the Doctor's presence no matter where they were. She knew the Doctor thought that it might be too much for her, that his mind was too old, too heavy, too dark, for her to want to be a part of it. But Rose could see the beauty in his mind, tempered by grief, and regret, and anger, yes, but no less poignant for all that, suffusing every strand. He was her Doctor, and she wanted to be a part of him, if he'd let her.

The only question that remained for her, though she was careful never to think of it when they were joined, was how long it would take until the Doctor's honour was satisfied enough to accept her answer when she told him she wanted the bond.