His first self asks and the Doctor says nothing.
The truth is that he still finds it difficult to admit to being afraid. And he is afraid; of many things, but right now he’s afraid of change.
It took so long to find himself again, after that last change. At first, it was like being adrift on a raft in a vast sea; he’d been clinging on for life, never knowing where he was or where he was going as the waves buffeted him back and forth. He was rude and angry and for a long time he hadn’t liked himself very much. His thirst to see the stars had been whittled away by skin that felt too small, that made him tense up when anyone touched him. Sensations were overwhelming and difficult to process, and most of the time he just wanted to stay inside his TARDIS and ignore the universe around him. He’d never, ever wanted that before.
It might have been his worst regeneration yet. He still doesn’t know whether it was the result of starting a new regeneration cycle or if all his regenerations will be like that from now on.
He’s frightened that they will be.
Even without that fear, it’s exhausting to have to keep on being someone else, to keep discovering himself anew. He isn’t sure if he can go through with it again.
He decides abruptly that if he does change, he’ll do it alone.
Clara had been there the last time, and he can remember that now. He can remember everything about her and so much of it is wonderful. And yet, at the forefront of his mind is the memory of being a new man – a man adrift at sea – and having a friend who almost abandoned him for it. He remembers now the exact way she looked at him: accusingly, as if he’d stolen away her best friend and she could never get him back. That isn’t exactly a good start. Regardless of the things that came after, he spent months-years-decades (who’s really counting, at this point?) feeling like this new him wasn’t good enough, that she only stayed because another man had asked her to. He’ll always love her dearly, but he wonders now that if she’d accepted him more easily in the beginning he might have had an easier time accepting himself.
So he’ll do it alone, if he does it at all. He doesn’t need to judge himself by other people’s standards; doesn’t need a second opinion on whether he’s a good man or a bad man, not when he can figure it out for himself.
And it might have taken a while last time around, but he had figured it out eventually. In the end, he’s just a person. An idiot with a box.
With any luck, that’s what he’ll always be.