first of all, if this thread had been made. please don't flame me. i'd appreciate any good posts and your time reading.
In my opinion,while kakashi and rin are fighting the mist, maybe kakashi noticed how the mists' actions are not attacking rin with a fleet like 100 shinobis. kakashi and rin wont do a thing to that.
maybe rin is some kind of special person for the mist. the mist want something from rin or rin herself. this is the reason why kakashi killed her.
And how kakashi reacted after stabbing her.
kakashi looked very depressed(who wouldnt be?) and you can see it in his face that he forced himself to do whats right.
what do you guys think? if this thread was already made. please dont troll.
EDIT:sorry but the pics arent working i fixed it 2 times. but nothing comes out when i clicked my thread again. so there just links.