It's when certain things or actions control you kinda? Idk how to explain. I do know a person with OCD might do things because they think 'if I don't ____, the house will burn down, my teddie will get ripped, more terrible stuff, etc'. A common misconception is that they like stuff clean. Not all do, but they may think 'if my room isn't clean I'll get robbed' or smth like that. They also feel the need to do things perfectly or in a s certain way if the OCD is more severe. The books 'puzzled' and 'just roll with it' give good examples of kids with ocd
