A character's backstory revolves around slavery and the traumas they have faced.
Vampires are shown keeping their human victims alive and then passing them along to other vampires to feed on until that human dies. It's really disturbing seeing the hopeless state of the humans while they are just being used as fodder and are half alive.
A bad guy transforms into a beastly creature, which can be upsetting for sensitive younger viewers.
The main antagonist is frightening. She carries around a human female and slowly feeds on her blood for a couple of episodes until she dies. It's really disturbing how hopeless the situation is for the human. The same antagonist has a disturbing background - they are described as keeping their victims alive to prolong their torture as much as possible. And before the victim can be granted death, they turn them into a vampire.