The Grimm Devil (RWBY x Chainsawman/multiverse fic)

This fanfic starts off with the journey of a multiversal traveling reincarnator, while traveling from Chainsawman to RWBY, the portal allowed the laws Chainsawman's anime abides by to temporarily inter-work it's way into RWBY due to Remnant's weak will created by it's lack of souls. The laws of existence from Chainsawman created one being from the absurdly off chance union of world wills, the laws of negative aligned created beings, and the universal negativity and fear held in the other world.
Calling it an abomination wouldn't be far off, nor would saying it's a child of both worlds be far off, as such- the being is unique, it's chance birth becoming entertainment for onlookers and controllers of the system.