These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
The Sleepwalker: Hassam Bin Hassam has habit of selling shoddy parts to airlines, which results in the deaths of nearly 350 people from a large plane crash, for which he had absolutely zero remorse. He would regularly beat his wife, son, and housekeeper. He abused his son for enjoying Western culture, despite enjoying it himself, and kills his own wife when confronted about his plan. 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: Ralph "The Fuhrer" Donnington is a Neo-Nazi in charge of the South Devon Chapter of the title biker gang. He is introduced trying to assault and possibly kill his 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 Fuhrer 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 there older two children, and the younger two only live when Dante escapes though the window with the baby accidentally injuring her in the process. To eliminate Dante as a witness he sends a gang member to try to bomb the foster home that Dante was staying at. When The Fuhrer 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. When protagonist James Adams gets a job as a server for the clubhouse, The Fuhrer threatens to kill him for delivering tepid food as a sick joke, and admits he does this with every new server.
From the Aramov series: 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 a family member Ingrid to transfer her accounts to him by torturing her stepdaughter Ning in front of her, then kills Ingrid; sends hitmen after his nephew Ethan to remove competition for leadership, who kill 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; has his informant in the clan try to kill the current leader, his brother Josef. In addition, Leonid was also a brutal Domestic Abuser who regularly beat, raped, and mentally tortured his prospective wife Tamara, threatened to kill their children should she try to leave him. Leonid ultimately had little to no regard for his family, and only cared about being in control of it.
Designated Hero: James sometimes falls into this, though he usually gets called out.
Die for Our Ship: A canon example with Dana in The General, who is now cheating on her boyfriend to enforce First Girl Wins, despite the previous book showing him flat-out refusing to get together with said first girl because of how unstable it'd been.
Family-Unfriendly Aesop: You can make easy money by breaking the law. Cool People Rebel Against Authority. Friends let friends copy their school work. Slack off at school and cheat a lot, and you too can get top marks in your exams and go to the best university. Cool people don't care about school, and certainly not church.
As well as the above, those selected for CHERUB are naturally quite smart and do actually do their work, it just isn't the focus of the story, much like the lessons in Harry Potter in the later books. Ignoring the last bit as being religious shouldn't be considered an aesop. Oh, and they get punished for slacking off as well, or have you forgotten the Deadly Training Area or the laps?
In addition, most of the series focused on James Adams, who isn't that inclined toward schoolwork. Had it focused more on characters who are more focused on studying, then we would have seen more.
Romantic Plot Tumor: James and Kerry's relationship is this, with it starting off as an interesting enough romance that slowly evolves into a plot that makes you want to slam your head into a wall every time it occurs.
What Do You Mean, It's Not for Kids?: 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.
The Woobie: 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.