They make themself a sandwich with what you have left, eat it, and leave. You get a Venmo payment for the cost of a loaf of bread and sandwich ingredients later.
Get someone to do a very long set of interviews, thought experiments, and tests to see what makes us different in order to isolate, regardless of whether we can tell which of us holds the evil position, what areas of belief can have a position than can be objectively called evil. It'd be hilarious if, after months of testing, it turns out the only difference we have is our opinions on marmite or pineapple on pizza.
My evil self would've already completed her villain arc in which all of her art would be Pikmin fanart, except it's actually Breaking Bad memes in varying degrees of subtlety.
So I'd become her sidekick and do the same. I regularly pretend to fight myself in the mirror so that I can get really good at fighting with any and all potential clones of myself, so on the off-chance she wants to try and fight me, I have the experience.
Congratulate him on being bad and ask for advice on how not to be nervous when talking to strangers because clearly he's got to have gotten over that if he's an evil counterpart to me.
Killing villains doesn't make you evil. Unless you were already evil which would make your counterpart good, and killing them is just in your horrible nature.
i ask them what happened to have things turn out like that
if they are the same person as me, and simply decided to pick the most hateful way forward each time a choice was presented to them - i'd probably turn around and try to never think of them again. Because at least for others i can understand how life could've pushed them towards the wrong path. But for myself i know that good choices were always an option, so my evil alternate self would have to consciously act out of spite and hate every time
We'll probably discuss who's actually the evil one and probably have to settle the argument with our fists. Hm, maybe not a good idea, I'm kinda of a pushover, so I'd probably just accept his bullshit and see if evil me could at least have a paid spot for me in whatever shenanigans he was doing