Harpy is a demon bonded to young eagle Kirstie Collier after unrequited love turned to malicious hate and a half-assed knowledge in the occult birthed something that had no business existing. Whenever Kirstie feels so much as friendship with someone, Harpy bursts out of her and visciously crushes that friendship or the chances of it becoming something more. While Kirstie hasn't completely turned into a recluse, she's known as all business and very hard working at best and very cold, emotionless and strange at worst. And anyone who meets Harpy, well, they don't talk about it much, not even with their therapist, though the demon does haunt their nightmares.

It's unknown how intelligent Harpy is. She's not much for conversation or even threats. Whoever is luck enough to manage to notice anything about her but how terrifying she is would likely say she as the cunning of a ruthlessly successful predator with some understanding of the urban environment around her. It's clear by Kirstie's demeanor that she's aware of Harpy and what the demon does and why. Just how the young eagle manages to hold up under all the pressure of being so possessed isn't known either but clearly she possesses more strength than she usually gives herself credit for.