Fred and George are twins, they complete each other, but at the same time they are different people. Do you know what is one of the most depressing things I've found out about the twins? They only got hurt when they were apart. Sorry if I've already mentioned this.
I love all twins, hence the name; except for the twins in Jyu-Oh-Sei: Planet of the Beast King. ~Spoilers~ The older one, Thor, can screw himself and his younger twin, Rai, dies in the first episode. ~Spoilers~
Umm he was brave and he knew he might not get out alive and he was fighting for one of the things he loved and knew what he was getting himself into. Oh and I don't think he wanted to leave George all alone fighting where's the fun in that? Also he was in freaking Gryffindor! He had the nerve to do it. I'm sorry I don't think he's coming back. (Sorry to burst your bubble)