I hate when main characters branch off from cannon characters. Its a lack of creativity. Youre basing your fragment of a character off of a lone character.
Example.
Claire Maximoff
Long lost sibling of the Maximoff twins. She has similar powers, but her magic is purple and her running trail is green. She was automatically enrolled as an Avenger.
Example of a REAL character.
Penelope Bruinswick
Born and raised in Metropolis. She sees the chaos being caused by Batman and Superman, and feels appalled by it. They hurt so many, and she feels like they are false hope. She takes it into her own hands to evacuate anyone she can whenever something happens, and she doesnt wear some gaudy costume.
I hate whenever someone uses cannon characters as a base for someones origin story. Penelopes origin story wouldve been about how she was raised and family matters. The story wouldnt start off being based around the cannon characters.