Lewis

How would your PC react to a fellow PC killing an innocent?: Lewis would react differently depending on the PC. If it was Filipe or Alexi, he would just move on like nothing happened, because damn that's scary. If it was anybody else, he'd ask them why they did it, and depending on their response, act like a normal person. This is room for interpretation.

Confronted with a fight?: Once again, this depends. If it's anyone bigger than him, he would try to get help from his allies. If anyone around his size, he'd try and fight them.

You're left to your own devices, and have plenty of free time to do as you please?: He would work on, now that he can, practicing his gymnastics once again and, more specifically, his parkour, getting around easily, etc.

How would your PC react to a close friend's death?: He would become distant from everybody else, and just go do his own thing more often than interacting with others.

A random person's death?: He would just brush it off. It doesn't impact him, so he has nothing to worry about. He's seen it before.