Redefining the Impossible

"You're asking us to believe you died, woke up in another body, and now CONVENIENTLY can't remember who you were before." Rose shook her head, "That's insane." "I never said it wasn't," the stranger murmured. The pink and yellow human sighed, "What's your name then? Do you know?" The stranger thought for a moment, "I think they call me the Doctor."