Honestly the ghouls seem so SU gem vibes to me. I mean like powers, abilities, the gem species(?) In general, how different they are from humans. How gems are literally made of light but create a physical form and their true form is their gemstone. Lot of people see the ghouls as made up of.. some sort of supernatural essence. How gems can shapeshift which I wouldn't be surprised if ghouls could too. How gems don't need to eat or drink and idk maybe ghouls don't but like to. They probably don't need sleep like the gems don't. I could possibly go on...
(This entire illustration was a big step out of my comfort zone and my ass yelling at google for the reference pictures of car interiors, I hate drawing cars but this idea was too good to pass up)