Take for example toxoplasmosis in cat shit. It gets into rats and alters their behavior, making them friendlier to cats. This causes them to get eaten by cats, propagating the parasite. Then there's another one whose name I can't remember, that infects slugs, causing them to engorge their feelers (which turns them red) and drives them to climb high branches, so they get eaten by birds which propagates the parasite. Alcohol, to the alcoholic, alters our behavior in very destructive ways, causing all kinds of misery our lives and in the lives of everyone close to us. When you factor in children of alcoholics who become alcoholics as a result of this wreckage, it really does seem like some sort of demonic misery spreading parasite. The host even tends to die from it. In the depths of my personal misadventures, I couldn't make myself not drink, even when I didn't want to, and knew I shouldn't. Something else was in control. Just something I've thought about recently.