In time Hellheart grew to be a large creature with a spiked tail, spines and seemingly random tattoos across his entire body, long sharp hair, and large clawed hands. He has been described as smelling of dry-roasted peanuts. Although a bit gruff, he shows absolutely no malevolence thought to be intrinsic to demons, and this is because of his upbringing under Professor Erskine, who raised him as a normal boy under his faith. Due to his physical inability to speak (since he lacks a mouth), he tells jokes telepathically, typically involving fire puns.