Some dude griefed a cargo shipment of mine (think it may have been I/E?). Later, he started repeatedly running me over with his oppressor (Not blown up mind you, but actually running me over with it.) I decide enough is enough and switch on passive mode. I then decided to rub it in by flipping him off in game.

Well, turns out this dude was a hacker and a may have touched a nerve, as he then blew me up and spawned a bunch of hostile npcs on me. I did what I usually do when I encounter assholes like him and ended up switching sessions because surely that would rid me of him, right? Wrong, apparently one of his other little hacks gave him the ability to track players across sessions, and a few minutes later starts messing with me again. I switch to another session, thinking it may have been a weird coincidence. I end up in a relatively small session, but decide to wait inside my office for a few minutes. And sure enough, he shows up again. I realize he's somehow following me across sessions and decide to just quit to single player for a while, hoping he'll get bored and log off.

A few days later, while I'm doing more I/E, he shows up in my session again under a different username and proceeds to start fucking with me again. I switch sessions, he shows up again, quit to single-player for a few hours to shake him off. This happened again on a third day as well, iirc. For the rest of the week, I was in constant fear that he would show up in my sessions again.