If it’s the latter, then you gotta make them…well…human! Let me give you an example:
Susie is the nerd at her high school. But Susie is also a mean ass bitch, but is sensitive when people are being mean to her. She struggles with authority, which causes her to often refuse to listen to adults or those who are at a higher position than her.
Susie, in this case, isn’t just the “nerd.” She’s a girl that struggles with real life issues and acts in a way that isn’t (in my terms) typical behavior for a “nerd girl.” While you are creating your character, throughout your story, make that character pull at your emotions. Make your character go through complex situations that is at odds with their morals and values.
A good story that does this is He Can’t Tame Me by Meila Summers. The male MC is very complex, in my opinion. He goes through tough situations no child his age should go through. It makes you sympathize with him. He’s the school’s “golden child,” but deals with grown adult shit
DON’T MAKE MARY-SUE CHARACTERS!