I need help with a book!?

I really wan to right a book about nephilim (half human half angel) and Angels in general. I can't really find anything about nephilim and I want to know all about them so I can be accurate. And I want to know more about angels and fallen angels. But with the Angels I don't want a ton of religious information more angel and fallen angel mythology! And if it helps I really like the books hush hush crescendo fallen and torment, that kind of angel