Disclaimer: I would never do any of this stuff
I’m a little sadistic, but pretty moral, so I’d probably go for vigilante justice (which I typically don’t agree with in the first place, but I also don’t agree with just going out and killing people either) so I wouldn’t feel too bad about what I’m doing. I wouldn’t just give people a taste of their own medicine, I’d OD them. Rapists would probably be my first target.
I’m a small female, so I’d probably lure them in by making them feel like they can trust me (which people seem to already, since they’re cool telling me things about them that they normally wouldn’t). For males, it’d probably be a bang gone wrong.
In the beginning, it would likely be all about submission. Whether by fear or pain, my entire goal would be to force them to give in.
After I got tired of that, I’d probably play with them longer. Torture their minds instead of their bodies. Use them as experiments that aren’t ethical. Truly test the limits of the human mind and body. What does it take to drive someone mad? Can they ever come back from the edge? And not just that, but actually try to perform a study that can actually be beneficial to someone else, but cannot do the study themselves because it isn’t ethical.
More than likely, their death would be an act of mercy in the end.
I know this doesn’t really answer your real questions, but I would probably change up my style a lot, not just because it’d make me harder to catch, but because it’s possible I’d get bored.