I am living proof that sometimes dark, cruel, and twisted things just sort of fall out of a writer's mind. Thankfully, it doesn't appear to have driven off any of my friends - although one has told me that reading that particular work made her want to go bathe, like, immediately, she hasn't run away from me screaming yet. But since I have no readers to speak of, I can't speak so much for the audience aspect.

Still, the only thing to do is to write it the way it wants to be written, whether it may alienate your current audience or not. There are always new readers out there, and what drives some away interests others.
Besides, you're right. There aren't enough Mamoru-viewpoint stories out there.