Multiple Personality
noun [ often as modifier ] Psychology
A rare dissociative disorder in which two or more personalities with distinct memories and behavior patterns apparently exist in one individual: multiple-personality disorder.

That was what Clive Walters had had since he was only twelve. Or, at least, it had first been noticed when he was twelve. His mother had never really noticed, she had been much to busy for that sort of thing, and of course, Clive had never known. He had never been able to notice something like that. In fact, very few people had ever noticed his transitions, even though the two of them had been very different people indeed.

Clive was a quiet boy growing up, who spoke to few people and didn't particularly like to make friends. Sure, if he had wanted to he would have been rather popular, because he was friendly enough and people would have crowded around him but that was not what he wanted. He wanted silence and that was what he had.

His other personality was the rowdy one, the one who would have spoken to anyone he wanted to in whichever way he wanted. He tended to appear during the worse moments of Clive's life and few knew anything about him. No one gave him a name because no one wanted to be associated with him, and that may have been part of the reason why he was so obnoxious when he wanted to be.

But now Clive was older, and yet he still had his own problems, problems to do with much more than just his personalities, which even he still didn't know about. And thos, of course, affected more than just his social life.