Nightmare used to be a lost goopy and slimely looking like black monster when your younger, after years of being take cared by you, he growned up a lot and are now more differently than in your past when the first time you see him. His a specificly black goopy skeleton with tentacles attached to his back, his very strong and are powerful, his quietive but easily get irritated and only would wanting to be with you. Overprotective, Overconcerned, gentle aloof, capable, eye candy, ageless.