More Fusions!
Half cause I'm a slut for them and half cause of Pumpkin's special ability he gains later~

See Pumpkin made a wish to help Nut and the others in exchange for his destruction, seeing as he was offered something in return for it.
Voodoo then told him that the more he suffers, the more he will be able to help the others; a riddle to his powers.

Ghosts reside within the Nether: a realm where dead things reside when they are still unable to pass through the veil and into the mortal realm (or somewhere else). But without Voodoo's assistance on special nights of the year, Nut and Pumpkin's friends are unable to interact with the mortal realm without mediums.

Nut is a medium herself, but she can only see and hear ghosts through the veil to some degree, and pass on messages. Pumpkin however gains a different power which, in tandem with Nut and the parties, allow him to physically channel ghosts through himself, leading to a physical transformation and allowing the Ghosts to control his body to interract with the world of the living. To do this he must synchronise his mind to that of the ghost, using his insight and empathy to see and feel as they do, and allowing the Ghost easier access to possession.
Some ghosts are able to possess when they're stronger, but most of the Skip ghosts aren't strong enough to do so without assistance, hence relying on Voodoo, Nut and Pumpkin to really interact with the world~

These possessed fusions with Pumpkin often lead to a collaborative mindstate where both residents of the body so as they feel, learning from one another as they do. Pumpkin learns to really let go and get wild as Chase, for example, whilst Arc learns that lounging around and savouring things is really, really enjoyable.