Fiends
in CreaturesSome beings are by their very nature influenced by the darkness that formed in one direction of Realmspace as it expanded. They are native to the nether realms, especially Nine Hells, Gehenna, Hades, Carceri, and the Abyss.
The different kinds of fiends vary widely, but they are all shaped by this twisting force. It is also why the devils changed the way they did as they fought the Blood War.