Twelve times he had gone through the agonizing shock of regeneration.
Twelve times he lost control of himself, lost his memories and slowly and painfully regained them.
Always slightly dazed and confused at first, catching up again with his surroundings, with his body, with his companions, if he had any.
The last time he was lucky: a thousand years of knowledge and craziness reborn in a young body, gangly and uncoordinated yes, but strong and buzzing with energy.
This time he could feel it wasn’t so smooth. He could feel a certain amount of stiffness, some tiredness even before the regeneration was complete, down to the bone, as if the new body was already used, and worn, and raggedy.
He was the raggedy man, last time he presented his new self to a very young Amelia Pond, but only because his clothes were crumpled and he was confused and the Tardis was burning, and all was upside down, well beyond his control.
Now he felt raggedy inside.
He moved clumsily, trying to grab the Tardis console and stand, and felt someone by his side steadying him. A small voice, a little bit shaken, addressing him “Doctor, are you all right?”
Big eyes, round face, lovely hair.
“My Sarah Jane! I’m not bloody all right, am I? Rough regeneration, isn’t it?”
“I’m not Sarah Jane”
“You’re not?”
He was halfway slumped, halfway standing, one arm across the console, the other wrapped to the shoulder of the lovely big eyes-round face, staring at him, concerned.
“Not Sarah Jane… no. Not Rose either, you’re not blond. Because Rose is blond, even Martha knows that and is upset, because I’m a dirty old man longing for blond girls! But that was the other me, some time ago… So…”
He tried to straighten himself, putting the girl at arm length and using her shoulders as leverage. He was dizzy again and puffed out some vortex energy.
“Clara!”
Big eyes-round face smiled warmly, looking intently as the Doctor collected his bearings.
Clara, the girl who had travelled through all of his timelife to save him again and again: she knew all about his regenerations, she knew how it worked and how dangerous it could be sometimes, and she knew that his face would change, all of his body would change into someone else entirely.