Nightmare was once the Guardian of Negativity. When Nightmare became corrupt, he wanted everyone to understand what he felt that day of his corruption... So, he declared himself the King of Negativity. He hired Cross, Dust, Killer, and Horror to work for him, promising they get everything they have ever wanted in return. However, he felt his feelings for his subordinates become more than just that, more like sons. Thats when he found you, wallowing away in negativity and self doubt.