Private
Of course I want to kill you, you are an abomination. But it has been decided, by those more compassionate than I, that you have some modicum of choice when it comes to your destiny. You are being given a chance that most in your situation haven't been. Go against your nature and become something better or give yourself over to what you were born to be and be destroyed.
Lucifer can father other children, ask him about Jack if you're curious. James Moriarty can find another partner, he's done it before. They will not give you a second thought once you have been obliterated, and they will leave you to burn if they think they can benefit.