Ok I have an sl in mind and its out of the realm of the ordinary
Read below the line to get hit in the face with INTERESTING!!
Basically Satan has declared war on heaven. So God sends one of his Angels down to negociate. The thing is though, God doesn't tell the Angel that Satan is her father. And Satan, being who he is offers a deal: Have sex with me and I will end the war. Our angel does and of course gets pregnant.
Thats the basic idea. We can brainstorm and also I am wanting to be the girl