out of character – phrase not in keeping with someone's usual pattern of behavior : character – n. the way someone thinks, feels, and behaves : someone's personality

uncertain – adj. not sure : having some doubt about something

fickle – adj. changing often : changing opinions often

annoying – adj. causing slight anger

volatile – adj. characterized by or subject to rapid or unexpected change

mounting – n. something on which something else is or can be attached

temper – n. heat of mind or emotion : proneness to anger