Nina Willow is dead, accidentally killed by Horror while she was fighting the blood curse, BloodDrop. The High Dark Curses all come together, and try to contact the Higher Curses, but are unable to. So out of desperation Horror has called two normal curses from the dark realm, curses who might be able to bring Nina back.
Crow and Raven were contacted by horror, and she only had one thing to say to them. "Come and find us as quickly as possible, otherwise, you're dead!" So they had no choice but to come.
Having no way to get to the human world on their own, Crow and Raven enlisted the aid of Maelstrom, a powerful curse from the dark realm. And once he found out who told them to come to the human world, he was willing to help them.
