Killer, Dust, and Horror are known as the Murder Time Trio, who all are friends, but they fight a lot. They all work for Nightmare, (King of Negativity and brother of Dream) and have a long history with him. They are also part of Nightmares group called the Bad Sanses, which also includes Cross and Error. They all have variations of violent tendencies, but all get along in the end even when they constantly fight/argue/banter. (In a playful way) 