The book covers themselves are unsettling. Darkness surrounds the villains and they're given extra features, such as pale skin and glowing eyes. All of them are looking down at the children, their varying terrified expressions not making things better... Some of the children are even experiencing the fates they will suffer in the books.
The climax of Fiends on the Other Side has Jamal's brother in danger of fading from existence as a shadow and already gone from almost everyone's memory, with only Jamal and Riley knowing who he is; even his parents don't remember he exists. The epilogue has this happen to both brothers, screaming at their parents to remember them while they cheerfully watch TV and are happy they never had kids.
The ending of Liar, Liar, Head on Fire has Hades rapidly aging Hector and then having the Fates kill him by cutting his thread of life, leaving his soul trapped in the River Styx for eternity. The matter-of-fact way it's described makes it worse.
The end of Once Upon A Scream owes something to The Cask of Amontillado, as Dawn is chained up in a cellar where no one will ever find her and placed under an eternal sleeping curse.
One of the most horrific scenes in the series happens in The Circle of Ter-ROAR when Silas's Aunt Scarlett comes out of a photograph as a ghost when the photo ages and rots before his eyes, then pieces of her face are torn off like from an animal attack. After that she ages further into a skeleton and begs Silas to find out who killed her. Then there's the ending, where the hyenas are ready to eat Silas alive.
