The idea of being f-ed up in the head is teased and toyed with, but in the end, the MC is all talk -- literally. He spends the whole of the game thus far arguing with himself about his sexual urges and his morality. Considering what his mother does for a living, this mf should not be this uptight.
He talks about wanting to get down with some girls from the gym, but at a party where they're both half nekkid and expressing interest, all this fool can think about is his exit strategy. WTF?!? There's only one scene where he finally stops the uptight psycho self talk and handles business.
The whole sister nightmare thing is a cliche and an unrealistic reach. That bedtime scene in the hands of a better writer could have really resonated. She should have sensed his intent but also felt the safety that comes from him being her brother. That very duality could have stirred fear, but also begin conflicting feelings (think Dexter and Deb). She could start to view and think of the MC differently. Imagine the possibilities here!
Too many games that deal with mental illness of this variety just don't get it. The MC getting himself into shape should be as ritualistic as it is athletic. Not just getting stronger/alpha to protect his family, but something more primal, as underneath he senses it's as much to overpower his female prey and subjugate his potential rivals and sexual competition.. just a thought.
The MC... I just don't have a clear view of either him or his motivations as yet. But even if he doesn't fully grasp his own "becoming", we (as the audience/players) should be privy to his unconscious secrets. We should be actively shaping and guiding his evolution into a seriously charming and disarming psycho.
All in all, however, not a bad start by any means. If done right, this could be something special.