First! i cannot believe you haven't watched it yet. srsly. hahaha
next! well, if you want to write a ffic you really should watch the movie so as to learn their personalities. Dont just, ya know, depend on the fan arts floating around the internet, they could be misleading haha, you know artists: they create their own version of characters and set alternate universes. the best reference is the original source
and goodluck with the writing!!