cracks knuckles You ask, you get.
I'm an idea factory baby. Pick the one you like most.
If eyes have a different color:
- was born with it. Could have been a reason other kids bullied him in the past. He hated to be treaten like that just because one eye is different for no reason. Covers it to avoid more bullying.
Blind eye:
- lost it due to a fight - anything goes here. Good reason to hate on the person who injuried him.
- lost it due to a gamble? The one he gambled with took his eye as payment.
- magic went wrong and something exploded in his face.
- some other random accident caused it. Childs play went wrong, or just got animal claws in the face
Eye has power:
- might be a cursed eye
- might be a power he obtained by performing some complicated ritual.
- might be a power he got by some powerful being in exchange for something else
Scanner/camera eyepatch is self explanatory - scanner helps with finding things, measuring things, being a GPS, etc, Scamera is good for spying and blackmailing. He might've stolen it or just bought on black market. Might've get it from a techie friend.
Wearing eyepatch as an accesory - exactly that. Fedora making faces? Check. Black trench coat? Check. What else to do to look more menacing that he already is? Eyepatches are the thing, mi amigo. You wear one, you get +50 intimidating points. Bonus points if the eyepatch has a skull on it. No better way to boost a villains ego and make enemies tremble. Buy now---
Btw I really like the guy.