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.
YMMV: Artemis Fowl
Alternative Character Interpretation: The first book deliberately aims for this by making sure that every time Artemis does the right thing, he can explain it away as Pragmatic Villainy. The psychiatrist who narrates the book argues that Artemis is a sociopath (though admittedly not a standard case by any sense of the imagination), and warns of the tendency to view him as more noble than he really is. Later books make him more of a hero, though.
Him becoming a hero is explicitly stated to be character development. In the Eternity Code, just before the mind wipe, he says that he might become the monster seen at the start of the series. The next book reveals that he was right.
Anvilicious: Book 6: Go green, and you'll save the krakens, stop poisoning fairies with Spelltrophy, and keep the world from dying. Plus, Artemis Sr. puts emission filters on every vehicle they own, including the jet and helicopter. Though the series has dropped environmental anvils all over the place since its beginning.
Ass Pull: Eoin loves this trope or owes it money. Technology of the series doesn't appear to have any consistency: numerous vital plot points happened just because fairy technology happens to be capable to do something we weren't informed of or has a limitation never brought up before.
One short story in the companion book is set in the period between the first and the second book, aka when Artemis was still a egoistic criminal mastermind and Mulch was believed to be dead by the LEP. Holly goes to stop Mulch in his tracks, but she isn't supposed to know Mulch is even alive... Well, let's make him wear a mask! Voice? Did we mention all the dwarves' voices are exactly the same and even the dwarves themselves can't tell one from another? Because now they are.
Author Tract: Humans suck! Humans suck! Humans suck! We've just described the driving thrust of most books in the series.
Though this can be Justified, as in the end of The Last Guardian, its reveal that its a Fairy who is narrating the entire series, so it would make sense that the whole book would be a bit prejudiced to humanity.
Broken Base: When the film adaptation of the series was announced, fans were divided on the possible casting on Holly's actress, particularly on her skin color. It doesn't help that Colfer wants Saoirse Ronan to play Holly which adds more fuel to the fire.
Complete Monster: Debuting in Book 2, Opal Koboi is a sociopathic pixie. When she got her position at the head of her company, she drove the previous owner, her own father, to insanity. Along with Briar Cudgeon, she organized the Goblin rebellion, taking advantage of the violent nature of the Goblins and planning to betray them to take over. When Holly and Artemis beat her, she plotted her revenge, and unleashed a complex gambit in Book 4. She escaped from prison using a clone duplicate (cloning is considered an unforgivable act to faeries, as one creates new life which dies easily and cannot think for itself) had Julius Root killed, framing Holly, and then she attacked and Mind Raped a very prominent humanitarian, and had him send a probe down into the earth, to reveal the Faerie people. Doing so she expected to cause a war between the two races. In the sixth book, it is revealed that she had been experimenting on critically endangered animals to make herself more powerful. In the eighth and Final Book, her past self-came to break her out of prison, and Present!Opal hypnotizes two other pixies, and has them hold her past self, and murder her, while she pleads for her to stop. Having killed her past self, any and all things she has made or influenced in her tech-corp. explode. Communications go down, cars explode, cell-phones and various guns explode, and even the humans have their planes go down in mid air, and global communications stop. She then manipulates a number of Faerie ghosts who have been trapped on earth and want to be released. She has unleashed chaos on a global scale, and wishes to kill off all the Humans and take power.
Copy Cat Sue: Minerva is bashed for this. She's not too bad a character and Artemis beats her almost easily but she was too similar to the eponymous character and the author was trying to ship the two a little too much.
For what it's worth, that book is a Dolled-Up Installment. Colfer realized that his new protagonist was a bit like Artemis and just decided to throw him in, demoting Minerva to a secondary character.
Idiot Plot: The entire berserker threat would never have occurred if they had simply shot the future Opal BEFORE she became all powerful.
It is admittedly implied to be a result of fairy society being based off of Actual Pacifism, so that they are neither legally allowed nor morally inclined to shoot a prisoner. Although that explanation doesn't make much sense given Artemis and Butler were also present and seemingly neither of them even thought of it.
They were present in the control room in Haven, not the cell block in Atlantis. They could suggest it but not do it. They probably did think of it but knew there was no point saying anything.
Inferred Holocaust: In The Last Guardian, a good chunk of technology, both human and fairy, ceases to function. This leads to chaos on both ends, but the humans bare the brunt of it as cities darken, people loot, medical equipment is useless, and airplanes fall from the sky. Nobody particularly dwells on this.
Nightmare Fuel: There is a civilization of advanced formerly mythical creatures living in the center of the Earth that have the ability to watch anything and everything we humans do. They can also turn invisible, mesmerize people, and they wield lasers.
They're also able to cut you off from the rest of the world with time stops, make people drop dead for no explainable reason with bio-bombs (you know how people drop dead from terror? Maybe it was the doing of the Fair Folk), and the majority of them view humans as inferior, if not outright okay to kill if it wasn't for the Masquerade.
Somewhat lessened when you realize that they are shit-scared of us, because Humans Are Warriors and Humans Kill Wantonly. Unlike them, we have no compunction about killing them either. Not to mention that all their weapons are relatively non-lethal(with the exception of plasma cannons and missiles), while even a small 9 mm bullet can easily pierce through Fairy suits and kill a fairy even with healing magic. Also Haven City only have a population of ten thousand people and its one of there largest cities, which gives you perspectives on how big there populations is. Odds are the entire population of New York City can Zerg Rush and defeat the entire fairy race no problem or just a well place nuke.
Running Gag: Someone asks an antagonist if their goal is "world domination" in each of the first three books only to be told otherwise.
Unfortunate Implications: "Mud people", what fairies call humans, is supposedly based on Greek myth. It's also a white supremicist term for non-white people. Irish or not, the author should really have looked into that.
The Untwist: In the first chapter of The Last Guardian, Dr Argon ominously wonders if it is really possible that Artemis has been cured of the Atlantis Complex in record time. He has, and the only thing we hear of the Complex for the rest of the book are a few fleeting mentions.
Though it does seem to have badly damaged his self-confidance.
Values Resonance: Despite being said in his time as a mob boss, Artemis Fowl Sr's line about buying gold as a reliable investment and keeping it safe seems far more resonant in modern times.