I've always seen feeders as being comparable to the same people that get off on snuff films. They are completely and totally aware that the object of their fetishization is getting sicker and sicker and sicker, is suffering, and will die....yet they continue down that path. They continue slowly fattening them and deriving sexual pleasure as their "partner" slowly dies. When the fattie becomes too sick and disgusting( bedsores, fold infections, yeast infections, diabetic necrosis...etc,) or dies, the feeder moves on to the next victim.