A trope featured extensively in and named by Jailbreak, Problem Sleuth and Homestuck. Shortly after a character is introduced, player control is switched to that character, usually with the statement "you are now this guy." Under this trope, the change in control can sometimes be irreversible by the player, or alternatively the pool of characters which can be controlled by the players can be expanded.
Subverted when it turns out that everyone was being controlled by a mushroom, and the changes in perspective were just changes in who it was controlling. Used straight up after the mushroom attained sentience.
Control switches to Myra Orre after a Red Darts incident.
"Haha. Just kidding. You aren't Terry at all."