So since Parrish is a supernatural, and after I saw that trailer, I read up about mythical creatures immune to fire and a lot of stuff came up but one of the more popular and one that i think might work is a Phoenix
They can live to be thousands of years old and still appear incredibly young
They were wise, intelligent beasts
And if they died they would be consumed by flames
Only to be reborn from the ashes
They were hella fine creatures too
I like how all of these 11-17 year olds are just going to school with vampires and werewolves and giant spiders and vicious three-headed dogs in their backyard, yet they need a permission slip with an iron-clad parent/guardian signature to go have a harmless butterbeer at the nearby wizarding village.
Okay, Hogwarts. Okay.