Because it's the one that harasses my family.

...he use to be a triangle but I guess he has a human body now.

I'm not actually sure if it's one he got with the gem or if he hijacked someone's body again.

Don't worry, mostly he just sticks to harassing people and alluding to me how he's going to descend the world into chaos when we get back home. I think he's taking this place as a vacation.