In the end, it's a peroxide blonde girl that finally grasps his war-torn mind and gives it the shake it needs. All it takes is someone running by his side again, hand linked in his, to bring him back to the kinder, better world that he'd forgotten ever existed.
The Doctor had sworn to himself that there would be no more companions, no more people dragged headfirst into his completely mad life. But there's something about her, brown roots and tongue tipped smile that makes him forget that he ever swore anything at all.
Rose changes him for the better.