SnazzGary's Helpful Tips on Mary-Sue/Gary-Stu and Bad Antagonists

When creating characters, make sure they aren't a piece of cardboard. Make sure they have a back-story. Make sure they have personality that stands out. A motive too. Don't do the SAO and have the antagonist forget his motive for killing so many people. Don't be like the cast of Shingeki no Kyojin.

Example:
Mikasa Ackerman from Shingeki no Kyojin. She is a Mary-Sue. Or, "A perfect character". Her personality doesn't stand out. She seemingly only cares and lives for Eren. Don't make characters like that. Make sure they have other purposes too.

Make characters like mine; Like Lucius. Who seemingly lives to protects Arthur, but deep down, that is not his true motive.
Like Yuffie. She strives to be a good knight, in order to show her father that she doesn't need to live a prim-and-proper life of a princess. Like Arthur. He wants to know the reason behind the time paradox, why it occurred when he was born, and his ties to Pendragon, and God of Death, Rema'lai the Fang. Even like Phoebe, who, despite her calming and nice demeanor, she is actually a backstabbing bitch who manipulates people for selfish reasons.
 
Example of Bad Backstory or one that makes no sense and shouldn't be there:Mikasa's. It's just so random. I mean, it is good back-story, but not for SnK. Her being sold as a slave or whatever, then along with Eren, killing the murderers of her parents at the age of 8-9(?). 

No.
Even Lucius wasn't that messed up when his parents were murdered. He did what a child would actually do. Freak the fuck out and find the nearest adult. 

Example of Bad Motives:
SAO's. That's all I have to say. He forgot why he killed so many people.


Examples of Good Motives:

Pendragon took the throne from Emperor Jack Rahl after killing him, causing a war between House Pendragon, and House Rahl. Thus, Jack's grandsons, Julien and Cedric, try and kill the whole  House Pendragon.

Another short post, but hopefully helpful. 

Snazz Gary----Out