He stood in the park each night under the same oak tree, always motionless and silent, just standing there. Just waiting. Sometimes people walked by. Occasionally they whispered to each other, wondering what exactly he was doing there and why he was there every night. Most often, though they walked by, barely glancing at him. After all, it had been only two months since what people had begun to call the Battle of Canary Wharf. It wasn't strange to see people still waiting for a missing loved one to return. Perhaps this man was doing just that: waiting for his lost love to return to him.

As it so happens, he was waiting, but not for his lost love. No, she was lost for good, he knew, trapped in another universe. There was no way for her to return to him, no matter how much he yearned for her.

No, this man was waiting for . . . himself, incidentally. He knew it would be soon, but he couldn't say when, exactly. And so he waited each night, listening in the darkness for that whining motorized groan that he knew so well.

Until, finally, one night, he heard it.

He waited a few moments until he saw him approaching. He was tall and thin, though not nearly so tall and thin as the Doctor waiting underneath the oak tree. The man stalked down the path, his head down, hands stuffed in the pockets of his large leather jacket. As he walked past, the Doctor saw that his mouth was turned down in a tight grimace and he suddenly remembered the intense pain and grief that this man was living with.

The Doctor waited until he had walked a few feet past him, then called out, "Go back for her."

The man paused, his back suddenly straight and rigid. Slowly, he turned on his heels, his blue eyes sharp, icy. "What did you say?" he asked slowly, his Northern accent thick.

"Go back for her," he repeated. "Rose." His eyes closed briefly as his lips formed her name, the first time since mentioning her to Donna.

The ninth Doctor's eyes narrowed. "Who are you?"

"You know who I am."

"You're lying."

The tenth Doctor shrugged. "How else would I know about her? Not so long ago I was you, standing there, staring at me like I'm a mad person, which I am, but you already know that, seeing as I'm you. And soon it'll be you standing here, saying all this to yourself."

The ninth Doctor stared at him for a while, then shrugged. "I asked her. She said no. She made her choice. Life goes on." His tone tried to suggest nonchalance, but there was a pain hidden under it that the tenth Doctor remembered quite clearly.

"Life?" The tenth Doctor scoffed. "That's what you call this? Don't try to act like everything's all fine and dandy. I was you. I haven't forgotten the darkness I lived in. The pain. The hopelessness. If you want to keep living like that, then fine. That's your decision. But you got a taste of light. Love. Hope." He smiled. "Rose. And I know that you're craving it. You need it. Right now, you're fighting the urge to run back to the TARDIS and drag her onboard kicking and screaming if need be."

"I'm not."

"You are. You don't want to admit it, but you need her. She's going to save your life, your soul. She'll bring you what you're too afraid to ask for."

In two heartbeats, the ninth Doctor was in front of him, rage rolling off him. "You don't know what you're talking about."

"Forgiveness." He glanced down at the ninth Doctor's clenched fists, knowing full well what was coming next. "Redemption." The punch came so fast that, even with pre-warning, he couldn't duck in time. His fist landed on his cheek, the exact spot that Jackie Tyler had slapped him what seemed like eons ago.

"I don't need forgiveness or redemption." He spat the words out like they were curses. "I don't want it. And I certainly don't deserve it."

"You're right. You don't deserve it." He rubbed his cheek sourly. "But you want it, and you do need it."

The ninth Doctor's fingers clenched the fabric of the tenth Doctor's suit jacket tightly. Then he released him and spun away. "You went back for her," he said. A statement, not a question. "You made your choice and got your forgiveness, fine. But now I get to make my choice, and I don't need her. She's just one more stupid ape stumbling around this planet. She'll live out her life of work and chips and idiots, and that's what she wanted. Why should I go back and beg for her to come with me?"

"Didn't you see her face when you asked? She was going to say yes, until that boyfriend of hers. . . ." He couldn't help the fondness that crept into his tone at the thought of Mickey. True, the Doctor had thought he was a worthless lump at first, but time and again Mickey had shown his worth, had pulled through. There was a soft spot in one of his hearts for Mickey now that he wouldn't be able to get rid of if he tried. "Until Mickey the Idiot clamped on to her and brought her back to reality. I'm telling you, one little push. . . . No, not even a push, a tap. One litte nudge, and she'll come running right in. And you'll be glad you went back."

The ninth Doctor dug his hands deep into his pockets, his back rigid. "900 years and I've never gone back for anybody. What's so different about this girl, then? She's not so special."

"She is, and you know it. We don't ask just anybody to come with us." Slowly, the tenth Doctor approached the ninth, laying a hand on his shoulder. "She's like. . . ." His eyes drifted shut, a smile creeping onto his face. "Light and gold and warmth and home. She's bright and soft and sweet, kind and caring and so, so good. And she's the strongest person I've ever known." He could feel tears pricking his eyes and a lump growing in his throat. "Without her, I would have died a thousand times over. She's the best thing that ever happened to me. She's the only thing. She's what keeps me breathing. What keeps me fighting."

"And this is what I have to look forward to?" the ninth Doctor asked. He spun around, raising his arm to knock the tenth Doctor's hand off his shoulder. The ninth Doctor looked him up and down, disgust creeping into his features. "A weak, lovesick pretty boy? All right then, if she's so special, where is she? Up and left you, like they usually do?" The tenth Doctor's stomach dropped, the cracks in his hearts breaking even further. "That's what I thought. Not for me, thanks."

The ninth Doctor turned and began to storm off in the direction he'd been heading originally, glancing behind him to throw a piteous look at him.

The tenth Doctor reached, and searched, until finally, he found his voice. "She's gone," he said, his voice cracking. He looked over to see that the ninth Doctor had stopped, his back still to him. "She promised me forever, but she's gone. I knew it was coming; I'd already lived through this conversation. But I was stubborn. I clung to her, so tightly, thinking maybe if I held her here, refused to let go, I could change it. I could keep her with me forever. But . . . I failed. She's gone. Lost to me, forever. The best I could give her was two minutes . . . to say goodbye."

He sunk to the ground, silent tears spilling out of his eyes. "You think you're in pain? That's nothing to what I feel. Everything hurts. My head, my skin, my hearts. It hurts to breathe. My hand keeps reaching for hers, before I remember that she's gone and there's an ache in the pit of my stomach. My skin crawls without her, longing for her touch. I'm broken. Completely lost without her."

The ninth Doctor was silent for a few moments, his eyes puzzled. "And you want me to go back for her? Why? Why would you tell me this, if you're trying to get me to go back? You say that she saved your life, but this. . . . This looks more like she condemned you."

The tenth Doctor wiped his eyes and shook his head. "Because, you need to know, that this pain. . . . It's worth it, for everything that she's given me. Like I said, she's the reason I keep breathing, even though it hurts. Even though I don't know what I'm doing right now, and I'm barely going through the motions. But she's the reason I know someday I'll move on. One day, it won't hurt so much, and I'll be able to look back at all our memories without being consumed with what I lost. I can see the way out, the light in the darkness. That's what she gave me. And that's what you don't have. That's what you need from her."

The tenth Doctor could still see the doubt in the ninth Doctor's eyes, but there was something else. A desperation to believe what he was hearing. A longing for resolution. He knew it would only take just a bit more. Just a nudge. He stood up, tears still leaking stubbornly from his eyes. "I'm not here, talking to you, because I have to be. I'm here because . . . if I could go back to this moment, when I was living it as you. . . . If I could make that decision again. . . . I wouldn't hesitate. I would run back to the TARDIS and I would beg. I would plead and cry and offer her anything in the universe to come with me. I would do it all over again, if it meant I could be with her. Because what you don't understand right now – what's stopping you from doing just that . . . is that you don't know that even just a second with her makes this pain worth it. All that time we spent together outshines any pain I'm feeling right now a thousand times over. I wouldn't give up those moments for anything. Not even to save the entire universe. Trust me, Doctor. You don't want to miss that. Go."

The ninth Doctor's face changed, his eyes widening, hope filling up inside him and spilling out. The tenth Doctor remembered the feeling exactly, remembered knowing for the first time in so long that he wouldn't be alone. That there was hope for him. Someone who wanted him, if he would only hold out his hand for her. He took a stumbling step back, and froze.

"What are you waiting for?" the tenth Doctor asked, waving his arms at him. "Go! Go back and get her, you bloody fool."

The ninth Doctor took a few halting steps backwards, then abruptly turned and sprinted away. The tenth Doctor watched him until he was out of view, then leaned back against the tree, his eyes drifting shut as he remembered the feeling he'd had when it had been him. The feeling of endless possibilities stretched out before him, and facing them with the most important woman in the universe together, hand in hand. The feeling of ecstasy, elation, excitement. The thrill of it. And the simple feelings of happiness, contentment, overshadowing all else.

At the moment, those feelings were gone for him. Stolen away with Rose. But he would find them again, maybe not right away, maybe not with his next few companions. But one day, he would find that feeling again. It would take time, of course, but he was a Time Lord, and that was nothing for him.

With a sigh, the Doctor pushed himself off the tree and made his way back to his TARDIS, his head down, his hands stuffed into the pockets of his slim, brown, pinstriped suit jacket. Rather than a grimace, though, he wore a sad smile as the thought occurred to him that, at this moment, as himself, he was alone. Rose was gone. But, in another time, another place, he was with her, and she was with him. The Doctor and Rose Tyler, travelling together through time and space in the TARDIS.

He never returned to that oak tree, leaving it silent and still, waiting for a man who would never come back. Sometimes people walked by. Most often, they thought nothing of it. Most of them had never even known that there had been a man who'd stood a silent vigil there every night. But occasionally someone would walk by who remembered that man, and in those instances they would remark to their companions about him. Had he given up? Moved on? Found another love to replace the one he'd lost? Or had he found her, finally, after days upon weeks of waiting? They liked to think that he had. So many people had lost someone that day in the Battle of Canary Wharf. They needed to believe that, for someone, the ending was happy. That he had found his lost love, and they were together, somewhere, happy.

And – in a way – they were.