M was arrested by the Police for attempted murder ("But he was asking for it!") but broke out after smuggling in bombs. M ran to the greatest criminals he knew: NintenD'oh. Their leader, Homer Simpson, allowed M to work for them, and M began a career there.
After NintenD'oh failed miserably, M was fired, and went to Nintendo to get revenge. Nintendo assigned M the job of hanging out with Mario so he would look cooler.
Ernie from Peppermint Park has a strange obsession with M, and even has a song dedicated to how he can't imagine life without M. You'd think M likes him, but in reality, M thinks he's a creepy stalker.