He knows, instinctively, that he survived when he should be dead.
He knows that he lost something.
He knows that he is missing something.
He doesn't want to know these things.
He is a man driven by one goal – to escape. The vehicle he has created will take him away, far away.
He is no ordinary man.
He is the best.
He is the Doctor.
It comes to him.
One day, so long after he remembers what he lost and who he is, he decides he is no longer needed here.
'I can ascend in the TARDIS once London is safe…'
His own words.
He asks his son, one day, ten years to the day after the Doctor left them forever, he asks.
'Is London safe?"
His little boy, now a young man, looks at him, and doesn't understand, so he answers as best he can.
"Yes, father," he says. "London's safe. It's been safe for years."
And the man, who at his heart still thinks of himself as the Doctor, looks up.
"Then," he says, "tonight is the night."
His boys eyes widen, and suddenly he comprehends, and they shake hands as equals. Then, he gets the coat and the waistcoat and the trousers, the clothes that he, the Doctor, wore, and he goes to his ship.
And she is there.
"Sir," she nods, and smiles. She is in the TARDIS. He smiles at her, and together, they will ascend.
It is, he reflects, how it was always meant to be…