"Hey, wait a minute – Doctor!" Amy scrambled after him with Rory bringing up the rear. "Just what was all that?" she demanded when they all reached the control room.

The Doctor ignored them in favor of taking them back into the Vortex. Once they were stable, he turned to them, observing their frightened faces. "Right, then," he said, "questions?"

"Yeah, I've got questions." Amy growled. "What happened?"

"Melody regenerated into River Song."

Amy almost snarled, and Rory put a restraining hand on her arm.

"Yes, Doctor. We saw that. But how? Why? She obviously knew you. Just as you obviously knew her. Despite the fact that you didn't recognize her. Sounds like she traveled with you. How is that?"

The Doctor slumped, rubbing the pads of his fingers over his forehead. "She's Rose Tyler. Or she was. She traveled with me for about four years. She was lost to an alternate reality."

"If she's lost, how is she here? And my sister." Amy asked.

"I did something monumentally stupid. I went back in time to the point where that world diverged from this one and built a bridge."

"You can do that?" Rory asked, eyes wide.

"With a lot of time and luck, yes."

"But-"

The Doctor held up a hand to forestall any questions. "I don't have all the answers. But I can guess at most of them." He folded his arms and leaned against the console, staring up at the ceiling for a long moment. "When I first built the bridge, I was too excited to think it all the way through to its most obvious conclusion. I built it, and crossed over. I never considered that once I opened the door, anyone would be able to step through."

"When I arrived, it was just in time to discover that she'd died. If only…" he shook his head, a mix of anger, frustration, and resignation sweeping his features. "When I came back, I went and sealed it through all of time. Only I can pass back and forth now. And only with the TARDIS." He put a hand fondly on the console. "But, in my personal timeline, there is about four weeks in which the bridge is still open. If someone knew me well, or was watching my movements…well. Four weeks is more than enough time to cross over, fake her death, and come back."

"And then…what?" Rory asked. "Brainwash her to kill you?"

The Doctor shrugged half heartedly. "Who better than a companion? I would never hurt any of you."

A pained groan filled the room, obviously piped in from elsewhere.

The Doctor looked up. "Ah, she's awake. Shall we?"

ooOO00OOoo

They watched from the other side of the one-way mirror, as Melody sat up, rubbing the top of her head. "That didn't go as planned." She mumbled, standing gingerly. She wandered around the room, casually poking the walls at random intervals. Not really looking to escape so much as discovering her limits. She completed the circuit, and only then did she settle down to inspect her new body. "Finally! I'm an adult again." She clacked her teeth together a few times. "New teeth!" She ran her tongue along them, testing their edges. "I'd kill for a mirror." Then she looked right at the hidden door from beyond which the Doctor was studying her. "That was a joke, Sweetie."

The Doctor grimaced and reached out, touching an unremarkable bit of wall next to the door. The door flared momentarily, then cleared, allowing Melody an unobstructed view of the Doctor, with Amy and Rory beside him.

Rory looked between Mels and the Doctor, at the electric eye contact that had been established. Then he turned to his wife and began to tug her away. "C'mon."

"But-"

Rory just turned and pointed at the Doctor, who had reached out and put one hand on the door, a look of heartbreak on his face.

"Right." Amy grabbed Rory's hand and the two of them left the Doctor and Mels to their reunion. They didn't go far, just around the corner. No way Amy was giving up this opportunity. But it was enough to give them the illusion of privacy.

"…Rose," the Doctor whispered, his voice a mix of wonder and pain.

She grimaced. "Don't call me that, please. I haven't been Rose Tyler for almost twenty five years. Call me Mels."

He just stared at her, eyes filled with a fierce sort of longing. "I'm sorry. This is my fault."

She raised a single eyebrow, tossing her unruly mane of hair over her shoulder. "In what way are you responsible for me trying to kill you?"

"I went back for you. I know I said impossible, but…I found a way and went back. But," he looked away, "when I got there…"

"They had beat you to it." She supplied in a soft voice.

He swallowed and nodded. "I spoke at your funeral."

"Oh?"

"Poetry."

She gave a wicked grin. "Shame I missed it." Then she tilted her head saucily to the side. "But I'm here, now."

He stared at her, jaw working. "Uhh…One fish, Two Fish. Red Fish-"

The sound of her body impacting the door reverberated down the hallway. She pressed a delicate kiss to the door over his hand. "Blue fish?" She smiled, "how romantic."

He gulped and moved his hand away.

Her smile turned wistful, and she settled down on the floor. He did the same. "All right, Doctor. Now what?"

"We wait and see if the Zero Room works to remove your conditioning."

She frowned. "Zero Room?"

"For Time Lords. Designed to enhance our telepathy and assist in healing damaged neuropaths. It might be able to set your brain into healthier patterns that free your mind from the conditioning."

"That's just the thing," she said, leaning forward, "I thought I had managed to free myself from it. Or I never would have contacted you." She paused, giving him a piercing look. "What happens if the Zero Room doesn't work?"

"The Zero Room was created by some of the finest-"

"Don't even try, Sweetie. I know you too well." She eyed him up and down, obviously liking what she saw, and he couldn't help but preen a little. But her gaze was calculating when she said, "let me rephrase. What happens when the Zero Room fails?" At his silence, she put her hand on the door by his face. "It will. You know it. Even now, part of me is trying to work out a way to get you to open this door so I can break your neck."

"No. The Zero Room will work." He insisted. "It will. It takes a mirror imprint of the latent bio-patterns left over from the previous regeneration. Then, in the event of a head-trauma induced regeneration, it pulls those patterns back up and assists in laying those old patterns over the new ones, allowing for some areas of growth and alteration due to regenerative dissociative cognitive divergence resulting from the new physical manifestation of the specific Time Lords genetic makeup, derived from the base biological Trioxyribonucleic acid, and then-"

"Stop with the techno-babble, Sweetie." She smiled impishly. "Your ten is showing."

He stared at her, at a loss for words. My ten is showing? He didn't want to be holding this conversation from the other side of a sealed door. He wanted to hold her. Wrap his arms around her and never let go. Kiss her breathless and tell her how much she meant to him. He thought he'd loved River Song. But knowing where she came from…well, he'd never stood a chance, did he?

They basked in the joy of being together; each unwilling to say what needed to be said.

She was the one who took the plunge. "You have to leave me."

"NO!" His response was instinctual. From the gut. His hearts teamed up to hijack his mouth, totally removing his brain from the equation. For even as he denied it, he knew she was right. He hung his head while she stared at him sadly.

"Oh, Doctor." Once again, she reached out, stroking her hand over the door by his face as if she could somehow touch him. Hold him. Kiss him as she'd dreamed of doing for two lifetimes now. "You know I'm right, Sweetie. We stay together and I'll just keep trying to kill you whether I want to or not. Madam was very thorough." She choked. "And I won't let that happen. I'll burn through all of my regenerations first."

"You can't!" he cried. Placing both hands against the door, he leaned forward until he was almost plastered to its surface. "You can't. You've got so much life to live ahead of you now. So many wonderful things to see! And I won't…be around…forever…" he trailed off as a thought occurred to him.

She laughed bitterly. "What makes you think I want to live in a universe in which you don't exist? Again?"

He stared at her for a while longer, then nodded as if coming to a decision. He stood, and she joined him, a look of confusion on her face. "Doctor, what is it?"

"I know what to do."

"Yeah?" and there went her wicked smile again. "Me?"

He stared at her, gobsmacked. He was used to River Song being incredibly flirtatious, but he'd always thought that it was something she'd grown into. But here she was, newly regenerated, and already making sexual jokes. It made him uncomfortable….and just a little bit hot under the collar. His eyes did a quick down-up along the length of her body, drinking her in.

The Doctor just checked me out! She thought incredulously. Never before had he responded to any of her flirts, and she had long since come to the conclusion that she was throwing herself at a wall. But it was a very nice wall and her flirting had never seemed to bother him, so she'd decided that if they couldn't be together, well, she'd get her jollies by flirting. But if he was going to respond….that just opened up all new avenues to her.

"I must admit, I like the new body. It's strange to have such light skin again. And I have no idea what I'm going to do about this hair. But…" she cut him a glance. "I think you like it, too."

He gulped and looked away, ruffling the hair at the back of his head nervously.

She laughed and took pity on him. "You never did say how it happened."

"Huh?" he said, his mind clearly elsewhere, and she smirked.

"I'm human, Doctor. Or I was. Humans don't regenerate. So how is it that I do? And do the same rules apply to me as they do you? Thirteen regenerations, right?"

"Thirteen, yes. And…I think it was Bad Wolf."

"Bad…really? I did this?"

"No. Not so much you as the Vortex. The Untempered Schism on my homeworld is the source of most of what made my people different from the rest of the universe. We have contact with the raw energies of the Time Vortex early and often. It shapes us. Gives us time sense, enables us to regenerate."

"And your massive Time Lord head? That from the Vortex, too?" she said impishly.

He shot her a glance, trying to tell if she was implying what he thought she was implying. But it was no good. Even this early in her regeneration, he simply couldn't read that smile. She might have been flirting again….or she might not.

She laughed and waved him off. "You're thinking again, I can tell. I'd ask what you have in mind, but…" she gave him a piercing glance and he looked away again guiltily. "You wouldn't tell me the truth anyway."

He huffed.

When he failed to say anything, she gave him a heartbreaking smile. "Your mad idea better work. I've already proven that I'd rather kill myself than hurt you."

He nodded. Touching the door once more in a gesture of good bye, he turned and disappeared down the hallway. But before she could even begin to wallow in the sadness of being separated from him, he was back, a comical frown on his face. "What do you mean, 'mad idea'?"

Her laughter echoed down the hallway. "Aren't they all?"

He raised his hand and opened his mouth to object. When she just smirked at him, he closed it with a click. "Right." Then he hurried away.

Once she was sure he was gone, Melody slumped to the floor with her head bowed, her back against the door. "Dammit!" she screamed into her hands.

"Mels?"

She twisted to see her sister and brother-in-law staring down at her worriedly.

"Amy, Rory, hey," she said, quickly wiping away her tears and plastering on a bright smile. "Sorry for lying to you-"

"It's okay Mels, I get it. Better than you think." Amy plopped down on the floor where the Doctor had been. "We're not linear, you 'n me."

Melody blinked. "What?"

"You know I've been traveling with the Doctor for about two years?"

"Yeah," Mels said warily.

"We've known you the whole time." Rory put in, settling beside his wife. "This you."

"What? How?"

Amy shrugged. "You've got your own time travel thing. Looks like a huge wristwatch."

"A Vortex manipulator?"

"You know what it is? I've never heard of it before."

Mels' face turned sour. "Once upon a time, I knew a guy." She shook herself. "So if we aren't linear, where are you?"

Rory stepped in. "We just finished the trees of Pern."

Melody gave him a blank look. "I don't know what you mean."

Amy laughed. "Oh, this is fun! No wonder. We can't tell you. Spoilers. Our past is your future."

"So I'll see you again? And I won't try to kill the Doctor?" Mels asked excitedly.

Amy and Rory shared an amused glance, then answered in chorus.

"Spoilers!"