IvyLuLu
What happens when not only the Men of Letters are out to get the Winchesters but a group of supernatural beings called nephilim are too. Offspring of the sons of God and daughters of man they call themselves shadow-hunters. Hidden from the real world they track down and kill demons and monsters, orders given to them by the fallen angel Raziel. Having had enough of the Winchesters screwing up things the Clave, the oldest and strongest of them, send Kova Denali, one of their fiercest warriors and her team to track them down. What happens when she catches up to the Winchesters and war breaks out among them and the Men of Letters. Can the she and Winchesters stop this war of monster hunters?
Set in season 12 of Supernatural. And yes it's a weird crossover between Shadowhunters and SPN.