Hell creatures are rather a very rare race of species found in the hell world. They all share black blood seen on their backs, they are also covered in skeletal type body fragments. They are like bacteria, they don't breed but multiply only from their black blood. It's like evolution by cloning.They can also be described as reptilian types.
They can only be killed by using the hell iron which can be obtained only from their skeletal bones and by shadow creatures.
Anything god-like can terrify them and will try to escape in anyway they can.
Many different packs reside in the hell world.
Soulless creatures as they are, killing each other to become stronger.
Hell seekers (bounty hunters in hell) catch them for their hell iron, to build, mould and upgrade their weapons, like using natural resources on the real world.
Hell creatures commonly hate each other, because it's of their demonic nature, having sinful activities and feed on each other's flesh.
People know that hell tortures by flames of fire, but here these hellion creatures torture the sinful souls instead of seeing them burn in hell.