* CompleteMonster: While many villains in the series [[EvenEvilHasLovedOnes have loved ones]] and/or are [[WellIntentionedExtremist well-intentioned]], these are neither:
** ''The Fall'': [[WouldHurtAChild Abby]] is the leader of a HumanTrafficking ring and, along with her henchman [[SerialRapist Keith]], stand out as some of the most depraved villains in the series. Abby has girls--as young as 11--kidnapped from Eastern Europe and either sold in the UK as {{sex slave}}s for willing buyers or forced into prostitution with them severely punished if they attempt escape. After one of her victims escapes, Abby sends Keith to recapture her, and Keith ends up kidnapping Lauren Adams as well. Keith will also rape woman captured by the ring, and later attempts to rape the 12-year-old Lauren out of lust.
** ''The Sleepwalker'': [[CorruptCorporateExecutive Hassam Bin Hassam]] [[spoiler:sells shoddy and faulty parts to airlines, leading to dozens of planes carrying hundreds being in danger, and]] the deaths of nearly 350 people from a large plane crash, something for which he had absolutely zero remorse. He would regularly beat his [[DomesticAbuse wife]], [[AbusiveParents son]], and [[BadBoss housekeeper]]. He abused his son for enjoying Western culture, despite [[{{Hypocrite}} enjoying it himself]], and kills his own wife when confronted about his plan to cover up his involvement in the plane crash. [[spoiler:When he finds bugs in his house, he brutally waterboards his housekeeper in the toilet and shoots her in the thigh so she can not get help. When cornered, Hassam holds his own son hostage at knife-point and threatens to kill him if he is not allowed to go free.]]
** ''Brigands M.C'': [[PoliticallyIncorrectVillain Ralph "The Führer" Donnington]] is a Neo-Nazi in charge of the South Devon Chapter of the titular biker gang. He is [[EstablishingCharacterMoment introduced]] trying to assault and possibly kill his [[AbusiveParents son Martin]] for spitting on a member's patch, only stopping when the member appeases him by having Martin fight the much more skilled Dante Scott. The Führer later threatens to kill Dante's father when he disagrees with his plans to have the clubhouse torn down for new facilities. When Dante's parents kill one of his thugs, he retaliates by killing them and their two older children, and the younger two only live when Dante escapes though the window with the baby, accidentally injuring said baby in the process. To [[LeaveNoWitnesses eliminate Dante as a witness]] he sends a gang member to try to bomb the foster home that Dante was staying at. When the Führer finds an undercover cop in his group he takes him to a field to execute him, until the cop tells him that he doesn't want a murder of a officer on his hands. Instead, the Führer has him cruelly dumped outside the house that Dante's family was murdered to [[KickTheDog mock him]] for failing to get justice for them. When protagonist James Adams gets a job as a server for the clubhouse, the Führer [[DisproportionateRetribution threatens to kill him for delivering tepid food]] as a sick joke, and admits he does this with every new server.
** ''Aramov'' series: [[EvilUncle Leonid Aramov]] is a member of an international crime clan that coordinates deals between cartels and criminal organizations, and plans to usurp leadership from his mother Irena. In his introduction in ''People's Republic'', he forces family member Ingrid to transfer her accounts to him by torturing her stepdaughter Ning [[ForcedToWatch in front of her]], then killing Ingrid; sends hitmen after his nephew Ethan to remove competition for leadership, with said hitmen killing Ethan's mother Galenka and his friend Yannis. In ''Guardian Angel'', Leonid kidnaps Ethan as a bargaining chip to get the Aramov accounts under his control; suggests cutting out Ethan's lower jaw and sending it to Irena as proof; takes him to a poacher's ranch where he is mistreated; and tries to overdose Irena on painkillers to take complete control of the clan. After being exiled from the clan in ''Black Friday'', Leonid moved to Mexico planning to sell weapons to the local cartels, and has his informant in the clan try to kill the current leader, his brother Josef. In addition, Leonid was also a brutal {{domestic abuse}}r who regularly beat, raped, and mentally tortured his prospective wife Tamara, and threatened to kill their children should she try to leave him. Leonid ultimately had [[LackOfEmpathy little to no regard for his family]], and [[ItsAllAboutMe only cared about being in control of it]].
* DieForOurShip: A canon example with [[spoiler: Dana]] in ''The General'', who is now cheating on her boyfriend to enforce FirstGirlWins, despite the previous book showing him flat-out refusing to get together with said first girl because of how unstable it'd been.
* HarsherInHindsight: The joke at the end of ''Man Vs Beast'' about Mr Large dog sitting Meatball becomes this after ''Mad Dogs''. See Mr Large's entry on MoralEventHorizon below.
* JerkassWoobie: James Adams is this in ''The Killing'' when all his friends ostrasice him for beating up Andy Lagan in addition to being severely punished by Cherub.
** Jake Parker briefly in ''The Sleepwalker'' when he breaks down in tears after making serious mistakes in his first major mission and is given a severe reprimand by Terence [=McAfferty=] and Lauren Adams.
* MoralEventHorizon:
** The Lambayeke cartel hitmen cross it in ''Class A'' by [[spoiler:torturing Junior to make Keith tell them where the money is]].
** Jane Oxford in ''Maximum Security'' ordering Eugene to kill [[spoiler:James and Lauren]] to cover her tracks.
** The AFM/AFA from ''Man vs. Beast'' are relatively sympathetic at first, and have a PetTheDog moment with the puppies they save from Ridgeway Kennels. Then they [[spoiler:kidnap Nick Cobb and force him to ingest large amounts of drain cleaner on a livestream]] and any potential sympathy goes out the window.
** Abby, Keith, Roman and the rest of the traffickers are already well over the line simply by virtue of being child sex traffickers. Keith then goes further when it's revealed that he rapes the children himself.
** Mr. Large finally crosses it in ''Mad Dogs'' when it's revealed that he caused a trainee to have a serious asthma attack by denying him his inhaler during a sandstorm. Then he tries to kill [[AndYourLittleDogToo Meatball]] when Lauren refuses to lie at his disciplinary hearing and strangles Kyle.
** In the same book, Sasha Thompson crosses it by beating councillor Chris so badly that he's permanently damaged [[DisproportionateRetribution for suggesting he step down as manager of Mad Dogs FC]].
** It's difficult to tell when ''The Sleepwalker'''s BigBad Hassam Bin Hassam crosses it, although a good guess would be either knowingly selling shoddy parts to the airline, leading to 315 deaths, or murdering his wife to cover it up.
** The Fuhrer crosses it right at the beginning of ''Brigands M.C.'' by murdering Dante's family.
** Dirty Dave from the same book sexually abuses young girls inside his club, and molests Kerry in ''Shadow Wave''.
** [[CorruptPolitician Tan Abdullah]] orders the demolition of Aizat's village to build a hotel and has Aizat and other protestors arrested and tortured.
** Leonid Aramov puts himself firmly over the line in ''People's Republic'' when he forces Ingrid to watch as he tortures Ning before killing her.
** Erasto/Hagar in ''Lone Wolf'' orders Fay's mother and aunt tortured to death in prison.
* WhatDoYouMeanItsNotForKids: The latter books have "Not Suitable for Younger Readers" on the back of the cover, presumably because of the gritty portrayal of sex and sexuality, obscene language, violence, drug and alcohol use, adolecent bad attitudes, etc. Unfortunately it never specifies how young is "younger," and is marketed as a juvenile book.
* TheWoobie: Ethan Kitsell/Aramov. His mother was killed, his life was destroyed, his uncle Leonid is a psychopath and actively tries to kill him, and his only friend is a double agent.
** Fahim. His father killed his mother and abuses him horribly, and he has no escape. He's given a brief HopeSpot when it looks like he might be able to become a cherub, but because he walks and talks in his sleep, he's disqualified. However, Mac takes him in, which is something at least.