It can be that the main character only turns evil, or something similar, when something bad happens, like in Zero or Naruto. In this particular instance, they no longer are themselves.
There is also when the main character may hulk out; like in the Incredible Hulk, where hes violent and dangerous, but still himself, deep down.
It can also be that the main character simply doesn't have the same moral boundaries as most people; so they're not really evil, however, they aren't 'good guys', either. Like the main characters in Ares, Akumetsu and Ubel Blatt.
Or maybe they become part monster, and thus see their boundaries start to change a bit, like in Aflame Inferno.
Please check my lists before suggesting anythin'.
Thank you.
________________
Quote
Does the walker choose the path, or the path the walker?