I love it when characters surprise you, just like real people. When I write a scene I just try to make the characters behave in a way that feels natural to them. Sometimes that means they make a left turn and do something unexpected. Those are always the best scenes in my opinion.
“Rule A: Don't. Rule A1: Rule A doesn't exist. Rule A2: Do not discuss the existence or non-existence of Rules A, A1 or A2.”