I had this idea that the MCs of my trilogy would have demon blood in them, and it keeps them safe from possession and they can sense demons (possibly). The possession immunity is what makes them able to defeat the villain. My question is, would it be too similar to the TV show Supernatural to have these characters have demon blood? In Supernatural, one of the MCs finds out he has demon blood in him. Turns out he is part of the villain's ultimate scheme. He has psychic powers because of the blood, and starts drinking demon blood (becoming addicted to it later).