I find that when I'm writing I have to think about how the character will react a lot. If you want something specific to happen, your character will have to respond in a way that they always have. For example, Lucy is a very passionate person and caring person not to mention a little self-absorbed, so trying to make her react in the ninja world is difficult. That's why I'm putting her through intense training so that it wouldn't be strange if she's ooc.