A Novel Idea

So, we all know that I want to write a novel, correct? *hears the crickets chirping, ignores it* Well, I wanna run something by you if you are reading this. I want to do a supernatural, vampire story that bites Twilight in the ass. If you're wondering, I want to do a vampire story where vampires are killers and not prissy, love-struck boys. So, here's the idea: it's going to be about a dhampire (half-human, half-vampire) that is also a PI (original, I know), who has teamed up with a cop and another PI in order to investigate a series of murders and disappearances. As he delves deeper into the investigation, he discovers a sinister plot to raise a powerful demon capable of washing the world in darkness. Oh and the reason he's a PI is because he's searching for the person who brutually murdered his (human) parents and abducted his sister, so maybe this investigation may hold some answers to his past and his true heritage
Sound like a good idea or too much like Angel meets Blade? You tell me. Please. Pretty please