He thinks a moment, leaning up against the shelves of books. "Well. To take a case at random, suppose you were presented with a patient who had, for a prolonged period, endured a magical effect with qualities of both normal possession and a state of horcruxification, and had been for that period more or less constantly subjected to a combination of the Imperius and Cruciatus curses from that source within his own body as well as an unending barrage of psychological abuse and manipulation. Suppose that this patient had, while under that influence, slaughtered unicorns and drunk their blood as well as attempting murder on several occasions, and who had furthermore undergone near, if not actual, death trauma.
"Suppose that, having been released from that durance several months before finding a healer, this patient finally presented with a very understandable increased timidity and decreased confidence, lack of interest in subjects that previously brought both interest and pleasure, sharply diminished intellectual and career ambition, brain injury resultant in memory loss with headaches, and a crippling fear that the possessing influence who had led him to acts so far against his nature was not entirely gone from him. Suppose that." He looks at Sirius inquiringly, as though it's an intellectual puzzle that doesn't matter much.