- Alternative Character Interpretation: Is Steve a troubled youth who genuinely cares for his brother and had his head filled with violent urges from horror movies and racism from his father, or is he a Manipulative Bastard par excellence who only refuses to kill Marty because he never did anything he perceived as truly wrong?
- Darkness-Induced Audience Apathy: The hero of the story is an increasingly unstable child, his brother's a racist serial killer, their parents are useless when they aren't abusive, and almost everybody else is a bully. So it may be challenging to really care much about what goes on, at least before the terribly bitter end.
- Jerkass Woobie:
- Marty. He becomes more like Steve as the days go by and he keeps his secret, but he is at least somewhat sympathetic, being bullied and ignored at school.
- Maybe Steve. Yes, he's a batshit crazy and racist serial murderer who violates his own mother before killing her, and his father, but there's some indication that he's just not all there.
- Moral Event Horizon: While Steve was always an insane, bigoted murderer, he officially crossed the line by murdering his own parents and leaving Marty bound and gagged to his bed.
- Narm: "You left oil on the driveway! Oil on the driveway! Oil on the driveway!" Said by Steve while he's torturing his father.
- Squick: The Film Within a Film Headless is filled with this. In particular, the killer's penchant for necrophilia as well as gouging out eyes and eating them. And the feature-length version is even worse.
- Tear Jerker: The entirety of the climax is this and Nightmare Fuel. After mercilessly butchering his parents, Steve talks to Marty, who's scared out of his mind. He tries to assure Marty that he'd never hurt him, and Marty breaks down crying while Steve begs him not to, mortified that he "made [him] sad". Eventually, Steve screams at him to stop before leaving him with the eyeless severed heads of their parents, and either of the siblings' final fates is left unknown. It's as heart-wrenching as it is terrifying.
YMMV / found.