On one of my initial versions of coraibolds (kobolds with a copper limb named "large copper dagger" in their right, non-grasping hand that was able to inflict a necrotic syndrome that sometimes transformed the victims into coraibolds) I had a problem with the transformed coraibold thralls still retaining their civ. I embarked on a coraibold cave and after a bit of fighting all of my dwarves were either dead from necrosis or transformed. I had planned that the transformed would turn against their former comrades but instead I was stuck with a fort full of coraibolds that are too small to wield a pick. (Funny thing that one of the former dwarf coraibolds had a romance with a dwarf migrant)
Those 'bolds also were a tad bit overpowered at one point. They could just stab an elephant in the head with their "daggers" and kill it. (usually while they were biting it and waving it around in air. Too high biting skill)
I have also had some interesting incidents with my current attempts to make a dwarven hive race. (a nearly immobile, slug-like hive queen that is the only breeding dwarf in the fort and soldier and worker castes.)
The workers are a bit like drunken tribbles with an ability to create an "aura of dwarfiness" as self-defence. Initially it was a dustcloud attack with a far too low cool down. You can quess the results.
A kobold snuck in the fort and boom, everything is flying against walls and getting killed by the dust. (nowdays it is a cloud of syndrome gas that causes nausea)
Edit: also, after a while a big chunk of the fort would be children of the hive queen and lead to the queen going insane over the constant deaths of her children