When a game creator takes a character they made super bitchy in their first appearance, and tries to make them super bad-ass for later appearances, but over-does it so much that they still seem super bitchy, just also over-powered. The original "Raiden Effect" of course being 'Raiden'c from MGS2, later to appear in MGS4 as a super bad-ass cyborg thing.
"Man, remember when Riku was a bitch in the first Kingdom Hearts game? He's got 'Raiden Effect' up the ass now." "Man, they took a weak whiny kid and made him the main character... The Raiden Effect strikes again."