Okay, I couldn't really fit the reason for Misto's attitude change in the fic, so I'll post this to clear that up. Basically, what happened was Misto was being taken over by an evil force. However, a small portion of the original him was still alive, so that bit of him was trying to stop the evil from killing anyone by pushing them away, and later, by killing himself.
Also, in case anyone was wondering, 'Sto arrivando, la mia anima gemella' is Italian for 'I'm coming, my soulmate.' :)
I hope that clears everything up!
Insane Tara, 'till insanity takes over!