Karma is basically the embodiment of the saying "what goes around comes around" which I believe means if you do something it'll come back to you. Good or bad.

I thought of Karma for two reasons. One: Karmatale sounds really cool
Two: you do genocide route in undertale, Sans makes you pay for your sins.

Karma is mute because karma can get you at any time and you could hardly know it. He's blind in his right eye because in his original AU Chara/Frisk stabbed him in the eye during their fight. When they reset there was a glitch which caused him to become blind.

His eye light now flickers constantly but he doesn't want people to see which is why he wears the eye patch.

This took too long to type.