I tried writing a Fanfic about F/SN before, but I wound up staying as close to the story as can possibly be.

my problem is a strange one, and I want to overcome it.

Because the F/SN characters-- No, because every other character ever is not my own, I often question whether or not I'm making them do something or say something they wouldn't ever say or do. Or I'll doubt that the character would ever behave the way I wrote.

I understand it's fanfiction, so I should just have fun with it, but I feel it would be more satisfying if I figured out how to overcome this problem.

perhaps a way I can understand the characters even further than whats already established?

also, I have no common-sense whatsoever, so I have trouble inferencing.