Harry Russell. Doctor Who. Lovely chaos. (№ 428927)

Whatever the Doctor did with her memories, it made her brain accept the story and find a way to reconcile it, so she was convinced that this was indeed what happened. Perhaps that was the only good thing that came out of the "accident" - her brain did it to cope with it, instead of a year or so of emptiness, if you put a thought in her, she could give it a rational explanation without question. Like a puzzle, any piece of which didn't fit, just reshaped its edges to make sure they fit and formed a slightly different picture, but one that Donna wouldn't question.