Beat him and give him something to really cry about.
Seriously though, I don't know how old your brother is, but if he's under 14 or 15 I don't think it's an appropriate game for him. Of course it's not over the top violent or gory, but the "demonic" aspect might be a bit much you know? With the Dark Brotherhood quests and other things like that, it may not be something an immature mind should be playing along with. Especially if he's crying about it. The rating "M" is there for a reason. Sorry, little step brother. The answer is "No."