One of my fav moments involved a fort I grew bored of.
I decided to end it with HFS and so sent my miner to the other side of the map and dug down, and stationed my military at the entrance to the tunnel. Nothing happened for a long while. I even sent a miner to dig out admantium from inside the pit. It wasnt until I set a stock pile for admantium and watched as the civilians marched out across the map and down into the narrow tunnel that things turned Fun.
Apparently a frog demon had made its way out before this and was hanging out of detection range near the entrance to the tunnel. As the first peasant was leaving with his load of admantium, he showed himself and slaughter the helpless dwarf before being pounded to death by my 6 legendary wrestlers/hammerdwarves/axedwarves. These brave soldiers then proceeded to fight their way into the tunnel as terrified civilans fled from the army of frog demons. Things went well, the soldiers even killed a higher demon with only a few minor wounds. Then they came across another demon and its SoF lover. The pair quickly killed 5 or the 6 champions, the 6th was left with a broken arm and missing both eyes, but alive as the pair made their way out of the tunnel and into the world, where they slaughtered a seige for me.
The surviving soldier groped his way blindly, deeper into the tunnel, stumbling apon more and more frog demons, terrified by the atrocities he saw visited upon his fallen friends before loosing his site he made no attempt to fight these demons, instead he fled allowing the monsters to beat and torture him. By the time he reached the pits both his legs had been pulled off, and most the rest of his body was severly damaged. As he neared the edge of the pit another demon appeared and the soldier, with a feirce cry grabed it and slid off the edge into the void.
After that it was your standard fair of helpless civies being raped by horrible demons.