* JerkassWoobie: For some, Nadia.
* MagnificentBastard: A few. Lord Loss. The Kah Gash. Beranabus.
* MoralEventHorizon: Lord Loss does this in his [[EstablishingCharacterMoment very first appearance]], with slaughtering Grubbs' family in a most cruel and horrific manner, and giving their bodies to his minions as toys.
* NauseaFuel: Some of the Gorn, and a few demon realms as well. Like that one from The Board in ''Demon Thief''. You know the one...
* NightmareFuel: Begins just from looking at the cover of the first book, and once you actually read it...
** What stands out particularly is the ending to the book ''Bec'', where the titular protagonist/narrator gives a rather detailed description of the various demonic beings she is surrounded by while trapped in a tunnel underground, as the light fades into darkness. And then gives a very graphic description of the sensation of being eaten alive by the various creatures (with claws, teeth, beaks and tentacles), with the implication that the last thing she ever hears is the sound of her own agonized screams echoing in the dark.
** Kernel having [[EyeScream his eyes stung out]] by the crab-scorpion demon known as Spine. Especially when the monster spits gelatinous eggs into his sockets which hatch crawling multitudes of multi-mouthed maggots, who then attempt to eat through his severed optic nerves and into his brain. Slowly.
** After Juni Swan's [[ImpaledWithExtremePrejudice de]][[StalactiteSpite ath]], she is resurrected as an AxCrazy undead... ''[[HumanoidAbomination thing]].''
* TheScrappy: Nadia Moore / Juni Swan.
* SlowlySlippingIntoEvil: Grubbs does this toward the end of the series after he allows his Wolf side to surface and, in his words, "becomes a mix of human, magician, wolf and Kah-Gash." These acts range from allowing Antoine Horwitzer to be slaughtered to ripping out Kernel's eyes because he refused to help with Grubbs' cause. He gets better though.
* TearJerker: Innumerable instances of tragedy abound throughout the saga and Lord Loss would relish every drop of it.
** Grubbs' misery at having never apologised to his sister for the cruel rat guts prank before she's slaughtered by Artery. This sends him into a massive downward spiral of depression in the institute where he is committed and nearly sinks him into catatonic insanity.
** Kernel returning home to his parents after being missing for ''[[YearOutsideHourInside seven years]]'', though he'd only been in the demon realms for three weeks. They try to make the best of it but silently resent his return so much that he pledges himself to Beranabus and returns to fight the Demonata for the rest of his life.
** Bran disrupting the ritual to close the tunnel, all due to his love for Bec.
** Bec's HeroicSacrifice to save Bran from being trapped in the demonic tunnel with her.
** Bec's ''[[EatenAlive horrific death]]'' and her [[RealityEnsues failed attempt to endure it with dignity]].
** Bill-E's demise and Dervish's anguish at not being capable of ending his nephew's life; even if it costs them the world.
** Bec confronting Dervish about his lack of care for her. After six months of living with him, he has only spoken to her so he could relive every moment of Bill-E's life through the memories she absorbed. Bec breaks down in tears at the fresh pain of loneliness after centuries without hope, Dervish is weeping in self-recrimination and pity and just when it seems that they will be reconciled; [[YankTheDogsChain the manor is attacked by werewolves]].
** Beranabus's LastDance and his FamousLastWords.
** Bec assuring Grubbs that she doesn't believe for a second that he is destined to destroy creation, despite it being prophesied by Juni. Grubbs is so overwhelmed by emotion that he [[{{Glomp}} sweeps her up in his arms]], sobbing.
* WhatDoYouMeanItsForKids: ''The Demonata'' is quite possibly the most extraordinarily hyperviolent children's series '''ever written'''. One of the tamest examples is Grubbs throwing rats' guts on his sister while she showers, just a few pages before he comes across her and their parents' savagely murdered corpses, in a room covered with their blood. Decapitation, dismemberment, infanticide, impalement, torture, mutilation and all manner of horrible deaths occur in every book, sometimes dozens in a single scene. To say nothing of all the bullying, kidnapping, animal cruelty and all manner of sins that the ''heroes'' get up to.
* TheWoobie: All three of the narrators, Dervish and Bill-E and ''ESPECIALLY'' little Bran, who'd grow into the surly Beranabus.
-->'''Bran:''' ''(mouthing)'' Fl-flower...
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