Grimm is the master of the Grimm Troupe, a mysterious travelling circus. In truth, Grimm and his Troupe travel from the Nightmare Realm to wherever the Nightmare Lantern has been lit by acolytes.[2] They gather Nightmare Flames from ruined lands to fuel the sinister being enslaving the Troupe, the Nightmare's Heart.[3] Their ritual to feed the Nightmare's Heart consists of feeding first a Grimmchild with Nightmare Flames. They then slay the Nightmare King for it to be reborn anew through the Grimmchild.[4