out of character
adjective
°Inconsistent with one's personality, disposition, or usual expected behaviour.
"The burst of anger was out of character for the normally placid boy."
°Not in character; not successfully performing within the mindset of a given character in a theatrical performance. See also .
"I was out of character for most of the first act because those people in the third row wouldn't stop chatting."
verb
°In a manner inconsistent with one's usual and expected personality or behavior.
°Away from the mindset, personality, or behavior assumed for a role that an actor is rehearsing or performing, or that a player is playing.