User blog comment:Zathronas/Analysis by an author - episode 11 Heroes and Monsters/@comment-26512661-20160207184016/@comment-24218038-20160207202209

When you write for this many characters, you have to remember their past. Any good writers will establish a past for their character even if he will never write it in their story. It gives you a base so you'll know how they'll react in any given situation.

It's one of two references you keep in mind (or on paper) that will always make you differentiate characters. The other is the personality you gave them. Both are linked anyway.