I have a revenge story, but the only reason I was exacting revenge upon this poor guy was because I didn't get to just kill him in the first place.
Way back in the days of .40D, I played a dwarven adventurer, all clad in his steel gear and ready to go. I decided, "Hey, let's massacre that entire human civ over there", as you do.
At any rate, I killed everyone. Except for this one damn swordsman. I never saw the man, but later when my adventurer died to something unrelated, I saw that he had fled the town while I was murdering everyone (In legends mode). I had even killed several large migrating groups, but not this guy.
He had fled to an elven forest retreat and was standing around there, for some reason. Goodness knows why he ran to the elves, but I decided that they needed a bit of genocide too. Made a new character, slaughtered all the elves. Couldn't find this god damn swordsman. Savescummed so I could go into legends mode. The fucker had fled once again. Where now, you ask? The dwarves. My own civ. So, I did what any deranged psycho adventurer (aka, all of them) would do. I massacred everything in my path.
Down, down, down into the mountainhome I went, killing everyone I found with my mighty axe. Finally, I find the bastard. Sitting there in the king's room. With three crossbowdwarves. I charge in, chop down the king. Bolts bounce off my armour. I slaughter the three crossbowdwarves. The swordsman chooses not to flee this time. He comes running. First swing, and I lose an arm. My shield arm. I return the favour, and all we have are our weapon arms. We take swings at each other, every time doing some horrendous damage to one another. Within a few rounds, we're bleeding out all over the ground. With one swing, he takes my head off, and bleeds to death the next round.
Totally worth it.