Statements as to which character is good or evil, along with statements as to why one does an evil or good run, all rely upon one's interpretation of the nature of good and evil, which depends, at least in part, upon ethical and metaethical philosophy. One must define good and evil before one can attribute the definition. Those definitions will be based upon arguments, which in turn shall depend upon ethical and metaethical philosophy.
Remember the human (This is a forum for a video game):