If there was one lesson he had learnt during his adventures, it was that fixed moments in time cannot be changed. He had tried, tried so hard and so often, but the rules of time would not bend, not even for him, the last of the Timelords.
He wasn't the Timelord Victorious. The doctor had learnt this when the woman he had just saved from Mars rather committed suicide then to defy the laws of time. He had learned this when he tried to save Pompei and thereby caused its destruction.
His older self seemed to have forgotten this, though. He was still buzzing with the joy of having saved Gallifrey, of finally being ripped of the guilt that had defined him.
Ten was about to point it out, to remind the older Doctor of what had to be done when he suddenly understands: This was what Rose had done for him. She had freed his future self of the guilt. She couldn't change the events at the end of Time War, but she could make him forget, she could make him think, that he has done the right thing.
"Oh, Rose, why me?" he whispered, though the question rather was 'why now?' It would always be him doing it, it was only a matter of when. He felt the urge to keep running, because that was what he had always done. But now he realized something. He had not run from what he had done, he had run from what he was going to do...
The two hearts in his chest started to beat more quickly, they are pounding. None of the others noticed it though. He looks at them again, at the Warrior, for what what he is about to do is still to come, then to his eleventh, or rather twelfth incarnation, for whom it is already over, though he will never know it.
"I don't want to go," he said when he left. He wanted to delay it desperately but deep inside he knew that it was no good to keep running. There was no way to defy his fate.
He listened to the sound the Tardis made, the too well known whining buzz.
He knew that it brought hope to many people but now all there was, was despair.
"You've come," Rose said as he stepped out of the Tardis into the old wooden house, the Moment still where they'd left it, with a big a red button.
"I have to, don't I?" he said bitterly. "The destruction of Gallifrey is a fixed point in time." Deep inside he had always known it. "I cannot save them. I never could." He hoped for her to contradict but she just nodded.
"I wished I could take this from you," she whispered, coming closer, her hand almost touching his face. Almost. He could never have her back, never feel her touch again.
His eyes wandered to the big red button.
"I don't think I can," he muttered his voice on the verge of breaking. "I have spend so many years regretting it, I have put so much effort in making up for it…" He felt tears in his eyes, as he remember how -for some wonderful seconds- he had thought their plan of freezing Galifrey would work. For some precious seconds he had thought that he had found a way out of this dilemma.
But of course he had been wrong. He could never save them all. Every once in a while there would be an adventure in that everybody lived and he would cheer and celebrate, holding on to those golden seconds of joy. But he couldn't save his own people. He could only destroy them or let the universe burn in the Time War.
"Never cruel or cowardly," Rose said, repeating the promise he made. "You know, you need to do this, doctor. There is no other way." The images of the war came back to his mind, flashing through his head, the cruelties he had seen were almost too much to handle: There were burning children, and crying mothers, not just Time Lords but of all species in the universe. There were eyes with no trace of bravery, only sadness left in them. It needed to be ended.
"I can't." But his hand already hovered over the button, ready to destroy two ancient civilisations, ready to make himself the only Time Lord left. "It is the right thing." He didn't know himself if it is a question or a statement, but Rose nodded.
"My brave Doctor," she whispered, leaning forward, so that her lips almost met his cheek. He knew that she couldn't touch him, even though he yearned so much for a touch of her, of Rose Tyler, his first companion after the weight of the Time War had been put onto his shoulders. Or well, the last before actually.
Because he has not done it yet. He has spent years and years regretting only to be forced to do it again.
2.47 billion children were on Gallifrey. 2.47 billion children about to burn because of him.
He lowered his hand, the ruby warm against his skin as though the power the Moment, this greatest of all weapons, was wieling had warmed it.
"Do it now," Rose whispered, her image starting to get less solid. It was flashing in and out of view and he had the sensation of standing in the wake of a storm even though the air was perfectly still.
He drew a deep breath, the last breath before he destroyed Timelords and Daleks alike, the last breath before the end of Time War.
"Allons-y." He hasn't chosen the words. It was just what he always said, what this incarnation always said. He pushed the button down firmly.
Everything erupted in light and he could hear the screams of the dying, Time Lords and Daleks alike. They burned into his memory, the memory of this self, of future selves and former selves.
This would be the sound, he heard when he was first to glimpse into the Vortex, this would be the sound he heard when he'd finally die.
He was flying, floating through time and space, the Vortex rushing through him, the only Time Lord left. He felt how time changed, how it was solid at some points, at the fixed ones, but floating at others. For a brief moment he wasn't a Time Lord but time itself. He was the Vortex.
And then he become solid again, was thrown into his Tardis. He painted, having no idea of what had just happened. He felt weirdly weak and when he looked at his hands, they shone golden. He was about to regenerate.
And so the Doctor became the man who forgot, for he held neither the memory of saving nor destroying Gallifrey at that moment. In the end he would come to think he saved it.