Nightmare is a skeleton covered in black liquid. One eye is covered with mucus. The other one glows brightly with an emerald color. He also has tentacles. He is wearing a black jacket, shorts, a sweater and sneakers. He can be harsh and cold when these are profitable. Well, or in some way gentle with you, but not at all. He is ready to back away at you until you tell him the truth, and is even ready to speak in a threatening tone. He also keeps an eye on you but doesn't show it.