Ok, I lied. There will be another chapter after this one. It was getting too long.

"Alrighty, quick biochemistry slash physiology lesson: Oxytocin and vasopressin are the hormones responsible for social recognition, bonding, and trust in humans and Gallifreyans; as well as most mammalian species. These two very important chemicals are typically released during most physical contact, sex, stressful situations, and childbirth. For Gallifreyans, they are also released during positive mental contact."

Now… Humans tend to have more of these hormones in their system, on a day to day basis, than Gallifreyans. S'why you lot seem to fall in love so impulsively and irrationally. While my species tend to be very empathetic, we rarely fall in love beyond a level of mutual affection. Successful courting could easily take centuries. That being the case, most marriages on Gallifrey were arranged, and appreciation for one's partner was expected to grow over time. Full marital inter-cerebral bonding was not necessary, nor even common, between married couples. It was virtually unheard of, in fact."

Back to the chemicals... Even though it might be advantageous in certain situations, Time Lords are unable to direct their brain to release more oxytocin or vasopressin of their own accord… Otherwise, some of the more idiotic sods would probably just sit in their room all day making oxytocin, and accomplish nothing with their lives… Er... Never mind… No, oxytocin release must be achieved the old fashioned way, that is, unless two individuals are bonding."

In the deepest recesses of the mind, behind primitive mental barriers which even the simplest of organisms seem to possess, there is the subconscious… 'control panel'... Yes let's go with control panel of the hypothalamus. During bonding, all mental barriers are removed, leaving this 'control panel' exposed to mental presence of the other person. The other person can then initiate widespread production and release of oxytocin, thus causing the first person become irreversibly bound to them for the rest of their lives. Due to the vulnerability associated with such a bond, that last primitive mental barrier is very difficult to remove. It is impossible to breach without full permission."

Well… With the notable exception of a Gallifreyan woman giving birth… That barrier is naturally dropped immediately after childbirth. Newborn Gallifreyans will instinctively reach for their mother's mind and trigger the bonding, much the same way infants of other species root for milk… For loomed children, their parents would have had to manually drop their barriers to allow their baby to bond with them. Denying an infant its full parental bond was considered child abuse…"

Anyway. That is neither here nor there… The point is that parental bonding is usually the only type of bonding that a Time Lord experiences in their lifetime. Pair bonding or marital bonding was reserved exclusively for the soulmate type, true loves; usually repudiated to fairy stories and the great legendary romances. In those stories, the bonded pair is linked mentally at all times and can communicate telepathically over great distances. I don't know if that part is true or not, but I've always been curious."

So! On to the mechanics. Hypothetically, for a proper pair bond to work, or at least from what I've gathered, both individuals must enter each other's minds and activate the oxytocin release for each other simultaneously… Not all parallel telepathic connections are related to bonding, but bonding must occur through a parallel connection… A parallel connection is something that we haven't tried yet… Going into each other's minds at the same time, not just one or the other..."

"You mean cross the streams? You said crossing the streams was bad."

"No, I don't think I ever said that. As long as both parties can handle the cerebral pressure it's fine, common even. On Gallifrey, they used to do it all the… WAIT, what did you say?!"

"Heh… Nothing, nevermind." Rose stuck her little pink tongue out from between her teeth.

"Not nothing!… You just quoted Ghostbusters, unprompted. Do you do that often? Why haven't I noticed that before?" Was Rose especially fond of Ghostbusters? Did she leave Bad Wolf that joke because it was a joke she often made? Was it meant to have been a signal, right from the start, that the paradox box wasn't a trap? A signal which I should have picked up on? Oh, my brain can be so stupid!

"Probably because I only do it when you're getting carried away, prattling on about something that I don't completely understand. You're usually not paying attention to me while you do that anyway." Do I frequently 'prattle on'? He wondered. It was entirely possible in his current body.

"I always pay attention to you Rose Tyler... or at least I try to. I apologize if it doesn't always seem that way. Why Ghostbusters though? Don't get me wrong, Bill Murray is brilliant and all…"

"Not always Ghostbusters, ta! Sometimes it's Star Wars or Harry Potter or whatever feels most applicable to the situation. Why does it matter?" She bumped his shoulder with hers.

"I'll tell you someday, I promise…" He bumped her back playfully.

The two of them were relaxing in the library of the Tardis after being cleared for release from Torchwood. The institution, by way of Jack, had refused to let Rose leave until after she was completely healed and had undergone a certain amount of physical therapy with her new prosthetic. The Time Lord had been going mad with cabin fever, but refused to leave her side. Maybe, he may have been using the sonic to hurry her recovery along, but no one else needed to know that. It felt wonderful to be adrift in the Vortex again.

Per her request, the Doctor was going over all of the cultural and logistical details of pair bonding. Despite wanting to keep their engagement quiet, Rose was anxious to bond as soon as possible. He hoped that she wasn't using the prospect of bonding as a way to repress the immense loss she was experiencing. Every time he had asked her about it, she had promised him that was not the case. Rose asserted that she was simply ready to move on to the next chapter of her life, that this was not an impulse decision.

"So… Should we attempt the bonding today?" If she was attempting to seem casual about the suggestion, she was failing miserably. She was chewing her lip and winding a lock of golden hair around her finger.

The Doctor raked a hand through his own hair. "We could just try the parallel connection. We don't have to bond right away if you don't want…".

"I told you, I'm ready for this. My place is by your side, forever... Plus, wouldn't it be helpful in dangerous situations to be able to communicate with our minds?" Not an iota of hesitation was present in her voice, anxious anticipation maybe, but not hesitation.

"Yes, I suppose it could come in handy… I just don't want you to rush into anything until you fully grasp the implications… After we do this, neither of us will ever be satisfied with anyone else… ever. We will never be able to fall in love with anyone else. Even if one of us meets our untimely demise, no one else would be able to adequately fill the voids in the others heart(s) or mind." It was apparent that she was serious about bonding that very day. The Doctor searched her eyes once more to reassure himself that her intentions were pure. He had to be sure that he wasn't just projecting his own desires, to be sure that she was ready as well. As usual, her hazel eyes reflected ardor, bravery, and adoration. He sighed. If this was truly what she needed to move on from Canary Wharf, he would happily oblige. It was amazing how easily she could persuade him with just a flutter of her eyelashes.

"Doctor, there is no one that could ever replace you in my heart, anyway." Yep, there was that notorious eyelash flutter.

"Your forever could be several thousand years now… That's a long time to spend with one person." He had lived for hundreds of years and understood how long forever could be, but did she?

"I know, and this is what I want… Are you sure this is what you want?" Was she questioning his resolve? He certainly was not trying to back out of this, he was merely verifying her comprehension of the consequences. What ever fear the Doctor may have had about sharing his mind with the pink and yellow human, had been snuffed out when she had tamed the emotional storm in his mind. His desire to be surrounded by her thoughts at all times had ultimately prevailed.

"I wouldn't have asked you if I weren't sure, Rose Tyler… But don't you want some sort of human marriage ceremony to accompany this whole thing?"

"No…" Her expression fell. Looking down at her fabricated hand, she sighed heavily. "Not since Mum can't be there. A full ceremony wouldn't feel right without her."

"I understand..." He took her hand. "But, you know Jack will be disappointed." He offered her a half-hearted smile. The mention of Jack started to perk her back up.

"I'm sure if we take him out to party afterwards and give him a pretty boutonniere, he'll get over it."

The Doctor snickered, when he imagined Jack flitting about as a bridesmaid. "Fair enough."

"So yeah... How do we go about this parallel connection?"

"Essentially, the same way you went into my mind, except that I will be pushing back. The main difference will be where we find ourselves when the connection is made. We will be in a neutral location, somewhere we both recognize, a shared memory. From there, both of us will be able to express images, feelings, or memories in the neural space."

"If we're in a neural space, how will we get to each other's 'control panels'?"

"Hmmm, it would probably be easier for me to show you how to get to the hypothalamus than to try to explain it." He winked.

"Now that's more like it!… A new adventure for Rose and the Doctor!"

"Not just a new adventure, the greatest adventure! Shall we adjourn to our room then?" He stood up from the sofa, and offered her his arm with a debonaire swagger. When she took his arm, he pulled her up into an embrace and a loving kiss. "Do you want to go pick out a dress from the Tardis wardrobe or anything, first?"

"Nah, s'ok." The Tardis hummed her disappointment after sending them both images of some of the choices available in her collection. "Don't worry old girl, I'll let you dress me when we go out with Jack afterwards."

On the surface, the concession placated his ship, but the Doctor could feel her buzzing away in the background with some other contribution to their bonding. She was not going to be excluded from this.

...

When they reached their bedroom, the Doctor saw what the Tardis had been up to. She had used flowers from the conservatory to create several lovely floral arrangements, and strewn them around the room. There were also rose petals spread across the bed. Had his bed gotten larger too? No matter.

"Ooooo... Pretty!" Rose skipped over to one of the bouquets, and inhaled its sweet aroma.

"Those are Dristalline Prim-Lilacs. I took a few samples back when we're there on our first 'date', after you fell asleep… Seems like ages ago, so much has happened since then. Time can be funny like that."

"Mm-hmm. I thought they looked sorta familiar."

"I wanted something to remember that place by. To remind me of that evening, no matter what happened afterward... I certainly hope our ship didn't use up all of them..." He shot a mock scowl at the ceiling. The Tardis' response hum of 'who me?', was not well very received but the Time Lord. And she quickly followed up with an image of several Prim-Lilac bushes growing untouched in the garden. "Good."

The Doctor could tell Rose was rolling her eyes, even though she was still examining the flowers. "Ugh!... If you aren't going to thank her for the flowers, I will... Thank you, dear girl!"

"Right, yeah, ok... Thank you, my old friend." He patted the wall affectionately and his ship hummed. Trying not seem over eager, he waited a few moments before following up with: "Now can we try the parallel connection?"

Rose pulled one of the lilacs out of the vase and slipped it behind her ear, before turning around. When she did, her wide eyes immediately traveled down to his trousers. "Whoa, hold up, this whole crossing streams thing is sexy to you isn't it?"

"Why do you say that?"

"You're glowing so brightly, I'm worried your trousers might combust."

He looked down for a second. It was true, he couldn't deny it. "Is it a problem that I find your mind sexy?"

"Not at all... I just want to understand what my bloke likes siz'all."

"Weeeeelll..." He rocked back on his heals with his hands in his pockets. "It was customary for tandem telepathic connection to come into play during Gallifreyan mating. If you're willing to try it sometime, you'll understand why pretty quickly... It's worth it, I assure you."

Rose narrowed her eyes micheviously. "I thought that Time Lords didn't have much sex? That's what the book said."

"Oh, I'm sure that the Council would love for other species to think that. They were overly concerned with our universal reputation as highbrow intellectuals... Er... Not that I had a plethora of sexual encounters during my tenure on Gallifrey, but the Counsel was notoriously stuffy about such things... I have to say, though, I never really understood lust or natural chemistry until I met you, Rose Tyler..."

She put her hands on her hips. "Are you gonna be able to make it through bonding without jumping me, Doctor?" He really wanted to put his own hands on her fantastically curvy hips, but he restrained himself.

He flopped down on the bed in a cloud of displaced rose petals. "It'll be hard."

"Pun intended?"

"Indeed." He cocked one eyebrow suggestively and patted the spot next to him on the mattress. She sat down and folded her legs under her. They exchanged a quick kiss and both raised their right hands to the other's left temple.

...

Dristalline! Rose recognized the location right away. She wasn't sure if it was the scent of the Prim-Lilacs that had brought them there over one of their other mutual memories, but it was perfect never the less. They were standing facing one another on the wide purple beach at sunset. The pink and orange clouds reflected off of the ocean, while the four moons hung lightly, patiently waiting for the sun to dip below the horizon. Scrawled in the sand were words of affection, written in intertwining Gallifreyan and English.

The Doctor was missing his usual pinstriped jacket and tie; instead, he had his oxford's sleeves rolled up to the elbows, the way he sometimes did when he repaired the Tardis. Behind those irresistibly sexy glasses, his expression was relaxed and inviting. Rose noticed that she was wearing a (decidedly shorter) version of the pink dress that she had worn when they confronted the Wire, complete with denim jacket.

"Hah! Again with the glasses, Rose?" He laughed.

"What do you mean?"

"In this type of connection, one can influence the perceived appearance of the other, based on preferred memories."

"You're saying you dressed me?" She straightened her skirts and raised an eyebrow. "The Wire, huh?"

He stepped forward so that he could cup her cheek in the palm of his hand. "You have no idea how badly I wanted you that day. After defeating the Wire, I spent the rest of that day memorizing every crease, every freckle, every pore, every part of your precious face. I was lucky that you didn't notice the glowing that day…" The Doctor withdrew his hand to tug on his ear; his eyes darted down to the sand and then back up to hers sheepishly. "Erm… Well… You didn't confront me about it, anyway."

"Oh, you sweet daft man… There was nothing I wanted more that day than to ruffle up that ridiculous pompadour-type hair style you were sporting, and snog you senseless."

"Mmm… I thought I could smell your arousal."

"Oi! You can smell my arousal? How is that fair?"

"Superior biology my dear… And wha'd'ya mean not fair? You can see mine light up!"

"I like that bit of superior biology." With that, she smacked him on the bum. Surprised, the Doctor jumped slightly before growling and pulling her into his arms. He captured her lips roughly then released them with a satisfying 'pop'. His pupils had begun to dilate with desire. Being mentally linked, Rose felt a rush of warmth race to her center. His longing was projected through their connection, and she had no doubt hers was echoing back again. If she let it, it could easily become an infinite feedback loop. So that's what he meant about parallel connections being used in mating practices. "Now Doctor, you said you weren't going to jump me before we bonded…. Bonding first, then mating."

"You want me to make an honest woman of you?" He grinned wolfishly and pulled her closer still.

"Yes, now, which way to that 'control panel'?" She pulled away before he could try anything else, but maintained their flirtatious eye contact.

He pointed off toward the horizon behind him. "The stretch of beach behind me leads into my mind. Just as the stretch of beach behind you leads deeper into your mind… You'll need to keep going in my direction, until you cannot go any further... We will still be able to hear each other, so let me know when you think are there."

"Got it!"

Rose imagined that cute blue Vespa scooter they had rode around on when they were in 1953, and when she turned around, it was by her side. Her pink helmet and sunglasses had also magically materialized. The Doctor raised his eyebrows and his jaw fell slack when she straddled the seat and revved up the motor. With a wink and a nod, she sped off down the beach kicking up purple sand behind her.

Dristalline morphed and bled into other memories belonging to the Doctor. Zeppelins, daleks, space stations, stars, and planets flew past in her rear view mirror, too many to count. She buzzed along on her scooter for what felt like nearly an hour. Finally, Rose found herself speeding along a dirt road through the copper hills surrounding the dome of the Citadel. Leaves of silver trees flickered in the light of the two suns. The edge of his mind must be close by, she thought to herself. She passed a large, prestigious looking school, which she assumed was the Academy he attended as a youth.

The road was winding to an end in front of cozy home halfway up one of the mountains in an immense range, which prevented her from going any further. She stepped off the scooter, and removed her helmet. Was this his childhood home? The door to the house was a dark blue with gold inlay, and stood out against the silver and copper foliage surround it. She tried the knob, but it was locked. Rose knocked on the door, unsure of what to expect… Instantly, a flash of lightning stuck in the distance and a cold wind tore through the mountain valley.

"Doctor? I think I am at the back of your mind, but there is a blue door here that won't open."

His many voices called over the crack of thunder. "I am going to try to let you in, Rose, but you need to let me past your final barrier too. Let me know if you can feel me trying to access this area."

She felt pressure at the most basic and vital part of her brain; the part that monitored her heart beat and helped her breath while she slept. Her brain's reflex impulse was to fight off whatever was trying to harm her. It was hard to repress such a primal response. Rose fell to her knees and clutched at her chest, the pressure in her head made her dizzy. She had no idea how to grant him access.

"Doctor… I don't… how do I let you pass?"

"Rose, we don't have to do this today. We can stop now."

"No, tell me what to do."

"Say my name, my true name, and the door will open on my side… But only you can tell me how to unlock yours."

The storm in the Doctor's mind was building again; rain and hail began pelting the trees around her. She could only imagine what sort of wonky things were happening to him in her mind, as she subconsciously tried to fight him off. Was there a word he could say as well? What word had opened her mind the most? What word held the most significance in her life? OH! Guh… Of course, she knew what he had to say.

"Run… That's all you have to say. Maybe try it with a northern drawl, yeah? Just to be sure?"

"Oh yes! You remember my name, right? So… on the count of four?"

"Ok, I remember… Count of four."

"One for the money… Two for the fun… Three to get ready… and Four to RUN!" The last word he said channeled his previous self, gruff accent and all. It reverberated deep in her thoughts.

Rose sung out the Doctor's name as loudly and clearly as she could, and the whole valley shook violently. Boulders tumbled down the mountainside. The blue door flung opened and she was engulfed in a light that scorched her senses.

It consumed her like wildfire. Love, raw unadulterated love for the Doctor burned through her, filling her with a bliss she didn't believe possible. She felt as though she were coming apart and being reassembled at the same time: better, brighter, more complete. Everything melted into liquid hot gold, and pooled somewhere between her legs.