Der Frei's abno story has always been pretty funny to me. The literary character he's based off, Max, is tricked into using magic bullets for a shooting contest that he needs to win to earn the right to marry his beloved, and those bullets were obtained by making a deal with the devil. The last bullet is cursed to strike his beloved, and the guy who scammed Max into this deliberately wastes all the other bullets to try to force Max to unknowingly kill his beloved. However, God intervenes and the bullet kills the scammer instead, and Max is just put on probation for a year and then he'll get to marry the lady afterwards.
However, the abnormality makes the deal himself, with the caveat being that the 7th bullet will strike his loved ones. So what does he do instead? He kills all his loved ones himself because he just really wants homing bullets and doesn't want any of them to be wasted. The devil seeing this is basically like "Damn bro you're worse than me I guess you can be the devil now" and dips, leaving Der Frei to be Der Frei. Man just really loves his aimbot.