Monster that feeds on suffering becomes a professional caretaker for people with chronic pain and terminal illnesses. They can't change the fact that these people are suffering, but they help a bit and in the meantime they're fat and happy off that Sweet Sweet ambient pain in the air.
Two towns over there's a demon lord trying to get their cult to abduct people for torture, but they keep getting stopped by heroes and the like, so they're barely scraping by. Meanwhile Belogarth the Registered PCA is chowing down on back pain, medication side effects and looming mortality for eight hours a day and has become the most powerful demon on earth without realizing it.