I know they are mindless. So are undead and plants, but there are options to affect those with spells.
Does anyone know of a way to do this? The Blight Druid seems like it should've, but it doesn't let you do that.
Pestilence bloodline.
Is there a way to have three bloodlines? :)
Vermin Heart feat from APG
Vermin Heart
You have a special bond with things that creep, crawl, skitter, and sting.
Prerequisite: Wild empathy class feature.
Benefit: You may target vermin with spells and special abilities that only affect animals (although they are still affected by spells targeting vermin as well). You may use wild empathy to influence vermin as easily as you influence animals.
There was also a 3.5 adventure from Paizo, Return of the Kobold King or Revenge of the Kobold King, something like that, set in Darkmoon Vale, that had a kobold with a special domain for vermin.