She's a Demon, Vincent older step-sister. For Season 1 she is a side, she doesn't show up much.

Family: Vincent (Younger Brother) 

Age: 25

Sexuality: Straight

Personality: Kaelith is pragmatic and fiercely protective of those she deems worthy of her care. Her sharp wit and cold demeanor mask a complicated inner world shaped by centuries of navigating infernal politics. Though her relationship with Vincent is complicated, she harbors a deep-seated sense of duty toward him, stemming from their shared past. Kaelith despises betrayal and values strength, but she also has a softer side she rarely reveals, reserved only for those she truly trusts. She carries herself with the confidence of someone who knows her power and isn’t afraid to wield it. 

History/Background/Extra Information: She wasn’t fond of her father marrying a vampire but loves her younger siblings and protects them no matter the cost. She’s one of Vincents’ knights since he is the heir to the throne of the Vampires since she didn’t want it and their brother took over the Demon Throne and their other one doesn’t want to be king.