Re: Later
"Personality change," John replied with a shrug before he tried to explain. "Each regeneration brings around not only a different body but a different personality. The memories are still there - most times - and some of the feelings depending on the personality, and some of the quirks of past regenerations comes out every so often."
His head tilted slightly to one side. "Oh him? Yeah, he was a bloody idiot. Sometimes they suffer memory loss too... I don't think that was his problem though. I wonder if the regen went screwy?" He shrugged. "Occasionally you get one of those. Be thankful you never met the sixth... We like to pretend he was some other Time Lord."