he becomes expert imitator

whenever he sees whatever his friend does, he'll imitate.
He especially likes to imitate what Gareth did; including what he says, his movements.
Whenever he sees his friends having something, he would snatch from him or her, and intended to throw it if ask him to let go and give back to the person.
naughty xiang bit him b4; now he know the tricks of biting when 2 of them fight.
He's too smart and too fast. 而我，束手无策，只能对他以牙还'牙'。