So as I said in the last chapter, I personally feel it is better to think of a setting before you create a character and of course, do some research into said time.
What I mean by 'applying a character' is essentially, making that character fit the time setting. E.g 'have some kind of correspondence or reasoning. Don't just have a monkey in space and not have a reason for it being there.'
Mary-Sue characters, though usually start out as average person, end up standing out from the crowd in a number of ways. One of these ways is that they could have been taken from another story. Let me explain:
If we look at Katniss Everdeen from the 'Hunger Games', she and her family are like many others in her district and even though she wins the Hunger Games, she wins it using a weapon that could have realistically been handmade in her district. She would have been a Mary-Sue had she won the Hunger Games with a Samurai sword.
If your character has a weapon, accent or any other feature that wouldn't have commonly been found in that setting or doesn't have a reasonable explaination for having it, it's safe to say they have Mary-Sue characteristics. E.g. Having blue hair in the Heian period, Japan.
YOU ARE READING
Anti Mary-Sue Character Guide
Non-FictionHere is just my list of tips of how to avoid creating/writing a Mary-Sue character. Take them as you wish. Greatest Achievements: #1 in non-fiction!!!