* AccidentalAesop: Just because you may have a legit grievance with somebody doesn't give you the right to take it out on either their personal belongings or their pets.
* AlternativeCharacterInterpretation:
** Are Christopher's violent, anti-social tendencies and general lack of empathy for others a symptom of his autism? Or is it more the result of the emotional and physical abuse he has suffered throughout his life?
** Christopher running off when he learns [[spoiler:his father killed Wellington]] is meant to be seen as an overreaction and another symptom of his autism, but on the other hand, Ed [[spoiler:reacted to a woman rejecting him by killing her dog and leaving the corpse for her to find, showing deep possessiveness, violent tendencies, and a controlling nature in one fell swoop. Even if it was for the wrong reasons, Chris could be right to think he isn't safe to be around.]]
* SugarWiki/AwesomeMusic: Adrian Sutton's soundtrack for the stage adaptation is very ethereal, but the music written for the Maths Appendix is the icing on the cake with a very techno beat.
* BaseBreakingCharacter:
** Christopher. Some fans like him because they find his view of the world interesting and liked the UnreliableNarrator aspect of his character. However, others find him hard to root for because of his insulting others for being less intelligent than him, and for coming across as a SpoiledBrat rather than the troubled child he supposedly is. In addition, some readers weren't happy with how [[HollywoodAutism Christopher's autism is represented.]]
** Christopher's father is easily one of the most divisive characters in this book. Despite his flaws, some fans sympathize with him when [[spoiler:his wife leaves the family for Mr. Shears,]] leaving him to take care of Christopher on his own. They see him as trying to be a good father and trying to make everything right for him. His detractors however view him as [[UnintentionallyUnsympathetic irredeemable]] for various reasons. This includes [[AbusiveParents being verbally and physically abusive towards Christopher, even when he was a child]]; [[spoiler:lying to Christopher about his mother being deceased for two years]]; and the most significant being [[spoiler:killing Wellington over being rejected by Mrs. Shears, Wellington's owner. The father getting no punishment from this or address his violent outbursts made some view him as a KarmaHoudini.]]
** Christopher's mother is also divisive. [[spoiler:Some fans despise her for abandoning Christopher because she is unable to deal with his autism and coming across as neglectful. Her blaming Christopher for her life crumbling apart also doesn't sit well for them. Others however try to give her the benefit of the doubt by trying hard to take care of Christopher and to connect with him, especially when he arrives from London. The scene where she kicks Mr. Shears out of the house for his treatment to Christopher is seen as a sign that she is trying to be a better mother to her son, though some argue it isn't enough to make up for abandoning Christopher two years prior.]]
** Readers are also split on Siobhan. Some appreciate her for being one of the only characters who understands Christopher and is a mentor figure to him. On the other hand, others criticized her for not acting on the abuse Christopher has endured, especially when he came to school with a bruise from his fight with the father and Siobhan dropped all discussion of this not long after, as well as her absence for the majority of the second half.
* BrokenBase:
** This book's portrayal of autism is easily the most contentious issue about this book. Some fans say Christopher is a sympathetic portrayal of autism and they show the struggles of autism for the time it was released in. However, others (especially some autistic readers) find it to be very problematic. They find Christopher to be [[HollywoodAutism another autistic stereotype;]] being a math savant, [[LackOfEmpathy having no empathy,]] and being a burden to others. They also felt that Christopher's tendencies came across as [[NightmareFuel violent and dangerous, especially moments where Christopher carries around a Swiss Army Knife]]. The author admitting [[http://markhaddon.com/blog/aspergers-autism/ he did no research on autism]] doesn't help with this.
** Readers are split on the resolution of the book, where [[spoiler:the father tries to make it up for Christopher by giving him a pet dog. This wins some readers over as they see it as him trying to make things better for Christopher as a way to say he's sorry. However others argue that giving Christopher a dog as an apology doesn't make up for killing his neighbor's pet, one that Christopher is attached to.]]
* CantUnHearIt: To those who got to see the theatre adaptation, Mickey Rowe ''is'' Christopher, partly due to [[ActorSharedBackground being on the autism spectrum himself]] and also because he nails Christopher's [[DeadpanSnarker snarky]] JerkWithAHeartOfGold personality perfectly by balancing Christopher's jerkish traits and actions with a demeanor that clearly shows he's a troubled and ultimately well-meaning kid. As such, many book readers hear his voice when reading Christopher's lines.
* CaptainObviousReveal: Readers will pick up on certain plot revelations, such as [[spoiler: Mr. Shears' affair with Christopher's very-much-alive mother]] pretty early into the story. [[Administrivia/TropesAreTools On the other hand, part of the book's appeal is seeing Christopher piece together this information as he slowly begins to understand other people.]]
* CharacterPerceptionEvolution: Even though Christopher was viewed as a progressive portrayal of autistic people back in the day, in the years since the book was released and many other representations of autistic people have been shown in the media along with a better understanding of autism, many people (Both autistic and non-autistic) began to see him as an [[HollywoodAutism autistic stereotype]] given his LackOfEmpathy and his tendency to be an [[SmallNameBigEgo egomaniac]] who belittles his classmates as well as his blatant AngstWhatAngst in regards to the emotional abuse he suffers from others.
* CondemnedByHistory: When this book was first released, it was viewed as one of the most progressive portrayals of autism and was praised for getting the reader to imagine the mind of an autistic person. However, many years after this book was released, especially around the late-2010s when autism became better understood, many readers have started to realize how problematic this book really was. For starters, while some autistic readers did relate to Christopher's problems, many others didn't and has criticized Christopher for his autism being stereotypical as well as his violent tendencies and being oblivious to any abuse done to him. Then the author eventually admitted he did no research on autism, saying that "imagination always trumps research," which angered many autistic readers. And finally, there has been a lot more autistic representation than ever before, with many autistic creators sharing their stories about their experiences with being on the spectrum. All of these combined has resulted in this book falling from grace after two decades of its release.
* DontShootTheMessage: According to the author, he wrote this book to get people to understand people who think differently. Problem is in this book, besides the fact that Christopher's autism was portrayed in a [[HollywoodAutism very stereotypical fashion]], he was also portrayed as someone who insults everyone around him (including his disabled classmates) while praising his own intelligence, and at worst threatened people with a Swiss Army Knife on two separate occasions. It also didn't help that Christopher is oblivious to any verbal abuse thrown by almost every other character unchallenged, even by his own parents.
* FairForItsDay: Today, this book comes across as a very dated and stereotypical treatment of autism, with little resemblance to the real condition. At the time it was written, however, such a sympathetic and nuanced portrayal of a person with autism was revolutionary and almost unheard-of.
* FanonDiscontinuity: Many readers agree that the book is ''much'' more pleasant to read if one substitutes Christopher's [[HollywoodAutism "Aspergers"]] for practically any cognitive disability, intellectual disability and/or learning disability that comes to mind. Even the original author [[InsistentTerminology eventually agreed with this claim]], asking to remove the word from the cover.
* {{Glurge}}:
** This book's portrayal of autism. First of all, [[http://markhaddon.com/blog/aspergers-autism/ the author in 2009]] has stated that [[CreatorsApathy he did no research on autism]] and said "imagination always trumps research", which didn't sit right with some autistic readers. Second, although the author stated that the message of this book is about understanding people who think differently [[InsistentTerminology as opposed to teaching readers about autism]], [[BrokenAesop some autistic readers feel this book did the opposite]] by making Christopher come across as [[HollywoodAutism a problematic stereotype (i.e. math savant, lack of empathy, burden to others, etc.)]] due to the lack of research into understanding autism. Third, every character in this book (except Siobhan and Mrs. Alexander) [[CrapsackWorld is verbally (and in a few occasions physically) abusive towards Christopher]], including authority figures [[AbusiveParents and even his parents]]. Christopher doesn't seem to be affected by any of this whatsoever, implying that autistic people don't feel abuse. Finally, even ''[[DisabilityasanExcuseforJerkassery Christopher himself]]'' is an asshole and, at his worst, can come across as downright [[MentalHandicapMoralDeficiency sociopathic]], as he [[SmallNameBigEgo derides everyone's skill and intelligence and praises his own]] and will kill anybody, armed either with his limbs or his Swiss Army Knife. This book was a success both critically and commercially to the point where it won several awards, earned itself a play based on it, and it still appears in pop culture.
** The ending can come off as glurge-y for some readers. [[spoiler:While the intention is for the father to give a dog to Christopher as an apology gift to show he's sorry, some readers find this hard to swallow. For one, the father was never punished for killing Wellington, and the violent behavior he's displayed were never addressed. And two, some felt the father's previous apologies came across as weak because at the same time, he acts like Christopher ignoring him hurts him and that Christopher is making this too difficult.]]
* InformedWrongness: [[spoiler: Mr. Shears]] calling Christopher a SpoiledBrat. It's meant to be a huge dick move that causes [[spoiler:Judy to leave him and kick him out of their house]], but it's not like he's actually wrong, considering how many readers have complained that Christopher's dad is essentially spoiling him rotten and enabling his bad behaviour.
* JerkassWoobie:
** Christopher's mother abandoned her son and her husband, because of being unfit to deal with having an autistic child, and it is clear in some letters that she blamed Christopher for the divorce, for driving her off the wall, so on, but we cannot help but feel sorry for her as well. She does feel remorse for hitting her son previously, most likely possibly due to convincing her that she could not be good enough of a mother for him, and she does feel anger at Ed for having hidden the letters from Christopher. She also threw Mr. Shears out after he yelled at her son, accused him of being selfish, and wanting him to go. She too wanted to hug Christopher, but could not. Though their negativity towards their son is not justifiable, it is at least understandable, and it is truly out of pure love, and mostly just due to overwhelming frustration.
** If one can look past him being UnintentionallyUnsympathetic, Ed, Christopher's Dad, could count. While [[spoiler: killing an innocent dog and lying to your son about what happened to his mother is not what any person in their right mind would consider acceptable,]] the fact that [[PlotIncitingInfidelity his wife Judy left him for another man]] and left him to raise Chris by himself is pretty sad.
* NightmareFuel: Christopher's dream. [[spoiler:To be precise, it is about a virus that spreads through certain facial expressions, spreading like a computer virus, and leaving alive only people like Chris that never look at others' faces.]]
** The ''[[FromBadToWorse real]]'' horror about this scene is that Christopher considers this a ''good'' dream. He is so isolated from other people that the thought of all the people he doesn't understand (and who don't understand him) dying and leaving him alone in a quiet and unintrusive world actually makes him feel happy.
*** To add even more horror, Chris's feelings about this dream show his ignorance of how much his livelihood actually depends on all these people he disdains so much. It doesn't enter his mind that he can't eat his favourite foods forever, with no one around to produce, distribute, and preserve them; or that he won't be able to watch TV or use the computer indefinitely, with no one around to maintain the power grid, the cable companies, the TV networks, and so on; or that the city would eventually be overrun with wild plant and animal life, which would create a host of new problems; or that the technology he relies on will degrade over time; or that without electricity he will be hard-pressed to live in any sort of comfort for most of the year; etc. Many of these problems would prove insurmountable, either for him specifically, or in general. The true horror of his dream is that if it actually came true, [[BeCarefulWhatYouWishFor it would be a nightmare]].
** And if you're on the autism spectrum or just have a good imagination, the sensory overload experienced by Christopher in London Underground definitely qualifies (shown very effectively in West End production).
** Christopher carries a Swiss Army Knife at all times and is not afraid to use it in self-defence. Given what he perceives to be a “threat” (i.e people actually trying to help him at the Tube station) this could lead to him attacking (or possibly even killing) a stranger in the future who only wanted to assist him.
* StrawmanHasAPoint: It's meant to show Christopher's black and white view of the world, but you can't blame him for being angry when [[spoiler:the police won't arrest his father for killing Wellington. He says it was murder even if the victim wasn't human. Wellington was a dog, but he was innocent of the fight between his father and Mrs. Shears]].
* TheyWastedAPerfectlyGoodCharacter:
** Siobhan. In spite of being both TheMentor and arguably the only ReasonableAuthorityFigure in Christopher's life, she [[ChuckCunninghamSyndrome just outright disappears]] later in the book with no explanation for her absence. Her reactions to Christopher's life and all the obstacles he must face are also either disappointing or non-existent, many critics argue that a helpful adult who recognizes abuse would've been exactly what the book needs to not fall vicitm to TooBleakStoppedCaring. Thankfully, in the stage adaptation, her role is greatly expanded, where she acts as the play's narrator, reading from Christopher's notebook.
** Christopher having a FriendlessBackground. While it ''does'' explain why he acts the way he does, it is also a wasted opportunity to show an autistic person empathizing and relating to a classmate who doesn't share their condition. Besides, many criticized Christopher complaining about his classmates to be an example of {{Wangst}} or UnreliableNarrator, given that only a handful of bullies were name-dropped.
* TooBleakStoppedCaring: All of the characters are jerks in some way, even the main character, so some readers will struggle to care about anyone or how the book will end.
* UnintentionallySympathetic: When Christopher finds out that [[spoiler:his father killed Wellington the dog]], Christopher immediately resolves to run away from home, concluding that [[spoiler: if his father could kill Wellington, he could just as easily kill Christopher too]]. This was intended to highlight Christopher's inability to differentiate between the two types of acts, but plenty of readers feel that isn't anywhere near the leap in logic that it was probably intended to be.
* UnintentionallyUnsympathetic:
** For all the crap he's put through, it's clear that we're meant to feel sorry for Christopher. However, the kid lumps all the kids in school together, calling them "stupid", ''[[TooDumbToLive hits a police officer]] [[HatesBeingTouched because he didn't like how he touched him]]'' and generally acts more like an [[TheSociopath uncaring]] SpoiledBrat than the troubled child he's supposed to be.
** Christopher's father also falls under this. While he does care for his son and accepts his differences, he's still described as [[WouldHurtAChild hitting his son when the latter was a child]] and ''continues to do so when he's a teen''. On top of that, [[spoiler:he kills his ex-girlfriend's dog for petty, selfish reasons. The book tries to make the father sympathetic by trying to apologize to Christopher, but at the same time the book is downplaying the severity of how bad his actions were and acted like Christopher is overreacting to the whole situation]]. It's safe to say that Christopher [[spoiler:and his mom]] were right to run away from him.
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