When Strickler orders Angor Rot to kill Jim, Angor Rot suggests that Strickler is too scared to take on the Trollhunter that killed Bular. Is that the case, or does Strickler hesitate at dirtying his hands by killing Barbara's son? While he is willing to use brutal force on Jim and can overpower him, he may be hesitating because Barbara would never forgive him if she found out. And despite him acting so coldly towards Jim, there may be that part that still cares for him and can't bring himself to kill him.
Is Not-Enrique being nice to Claire because he admits she's a casualty in her brother being stolen and swapped, or is it because he prefers life in the human realm? One thing to note is that he tries to stop the bridge from opening but gets blasted.
Angst? What Angst?: Claire never quite seems to react with the amount of worry one would expect after learning that her little sibling has been kidnapped and switched by a troll. In fact, the season 1 mid-season finale has her more worried about the play than her little brother. Granted, Jim assured her he was safe and the viewer knows he's safe, even if away, but she seems to have no rush in finding her brother during season one.
Badass Decay: Draal starts off the show as a powerful ally and foe, but starting with late season 1, he gets slapped around by basically every antagonist.
Claire. Some fans see a lot of chemistry between her and Jim, and value her position in the ensemble; others see her as a painfully generic chick and flat love interest. Athough this ends in a big way in the Season 2 finale, where she's psychically enslaved to Morgana, however some fans still have issues with her.
Some also feel this way about Toby. There are those who find his Adorkable behavior and loyalty to be endearing, but there are also people who see him as a generic Fat Best Friend, with lots of What an Idiot! moments and can be really pushy, if not selfish.
Jim knocking out Steve's tooth when the latter taunts him into a Rage Breaking Point. It certainly makes Jim and the audience feel better.
Barbara beating the tar out of Merlin with a broom, since she realizes that he manipulated her son into giving up his humanity permanently and made him disappear. Strickler holds her back at first, but she manages to land a few blows on Merlin, who shrugs them off with no remorse,
Likewise, Morgana tossing around Merlin like a ragdoll in the series finale. It was his idea to storm Trollmarket and take back his power, which made him seem very selfish, and he realizes that he miscalculated. Badly. And at this point he deserves it with how the Trollhunters made the better call in rescuing everyone from Eternal Night.
Complete Monster: Morgana, also known as Argante, Baba Yaga and the Pale Lady, is the true Big Bad of the series. An evil sorceress who helped Gunmar the Black rise to power to destroy humanity, Morgana was imprisoned by Merlin, but corrupted the once-noble troll warrior Angor Rot, using him as an assassin to kill trolls and Merlin's trollhunters. Possessing Claire Nunez to kill her friends, Morgana is later released and asserts her control over Gunmar's forces, the Gum-Gums. Killing most of Gunmar's followers to empower her spell to create an Eternal Night, Morgana launches an invasion of Arcadia Bay with clear instructions for Gunmar to massacre and devour most of the humans within before spreading out to conquer the rest of the world, with most of said world being destroyed to fuel Morgana's limitless ambition.
Cry for the Devil: A tiny one for Morgana; in the series finale she reveals that Merlin cut off her hand to make the Trollhunter amulet. Given that Merlin a few episodes ago manipulated Jim into giving up his humanity, this brief moment of rage from Morgana's part, even as she's trying to kill everyone, makes her moment sad.
Draco in Leather Pants: Strickler is pretty easily taken off the hook for going far beyond ordinary changeling evil of trying to take over the world for Gunmar by threatening Barbara Lake's life to come at a standoff with her son and secure his own survival. He may have regretted it, but the fandom still acts like the Lakes should be happy to throw out his past misdeeds out the window and welcome him into the family.
Fans Prefer the New Her: A genderflipped inversion of this as while some fans like Jim becoming a human-troll hybrid in the finale, many fans prefer him being human, given how disappointed they were when the finale revealed that Jim cannot return to being human as a result of him becoming a troll.
"Funny Aneurysm" Moment: In Season 2, Vendel warns the team that his ability to intercede in their defense is growing limited and the Tribunal, particularly Queen Usurna, is very unhappy with them. "I've stuck my neck out far enough for you hooligans. Any further and she's liable to lop my head clean off!" In the penultimate episode of the season, Usurna reveals she serves the Big Bad right before stabbing Vendel with a poisoned blade and then shatteringhis stone remains.
Season 2 was released the exact same day as The Last Jedi, meaning Mark Hamill was in two roles at the same time where one of his co-stars had long since died by the time it was released.
Draal getting captured and brainwashed by Bular becomes this when, in season three, he breaks out of the brainwashing and is horrified because he remembers everything he did. Then just as he and Jim reconcile, he pulls a Heroic Sacrifice to rescue Jim from Angor Rot. Jim is devastated by his failure to save Draal.
Jim's It's a Wonderful Plot moment from "Unbecoming" becomes this due to Merlin putting him in a dream where he never became the Trollhunter. Merlin had given him a pep talk to not give up the amulet to Usurna. Then we meet Merlin, who was expecting Jim to be in his early thirties and is a manipulative Jerkass.
Hate Sink: Usurna. She tries to take Aargh away from his friends without letting him have a say in the matter, leads the Tribunal in sentencing Jim for his part in releasing Gunmar, and when evidence of Jim's innocence is uncovered, she turns Vendal to stone and then shatters him to pieces to cover it up, revealing herself as Gunmar's spy and exiling Jim to the Dep just in time to allow her master into Trollmarket, giving him free access to all the trolls he needs to be brainwashed into his army. She's an Obstructive Bureaucrat at her very best and has few to no sympathetic qualities about her.
Heartwarming in Hindsight: Draal is antagonistic to Jim about the amulet going to a human child, and secretly worries that he's not worthy enough to honor his father's legacy. It's revealed that Draal has always been worthy, and was the alternative to Jim, in "Unbecoming". It becomes even more heartwarming in knowing that Draal wasn't chosen so he could live.
Mark Hamill plays a relative of one of the main heroes who became evil, just like he was fighting against in The Last Jedi, released the same day as Season 2. Dictatious is also blind, as Luke was originally planned to be in that film.
Strickler crosses it when he offers a museum guard to Bular as a "midnight snack" and jokes about it to Barbara later. If not then, he definitely crosses it when binding his and Barbara's fates together so that Jim can't kill Strickler without killing his mother.
Subverted when Nomura beats Jim to a pulp and gives him a nasty head injury, planning to deliver him to the changelings to open the bridge. In her next appearance, Jim forgives Nomura when she helps him survive a bout with a monster, and helps her escape the Darklands.
The antagonistic characters, as a collective, are called Gumm-Gumms. That's...not exactly threatening. This is lampshaded in the show itself.
Not-Enrique's real name is never given, and characters shouting "Not-Enrique!" at him in dramatic situations can be difficult to take seriously, especially when he almost drowns.
Popular with Furries: Troll Jim. Many fans find his design actually far more attractive than the usual looks for him.
Squick: Some trolls' eating habits can be... disturbing. Not-Enrique is fascinated with socks, the filthier the better, while several others express an interest in eating cat hair or meat. Worst of all, it's strong implied that Bular made a 'snack' of an unnamed museum security guard. It gets worse when it's revealed that Aaarrrgghh used to eat people as well.
Usurna intended to have the Amulet of daylight destroyed, saying that Merlins means of protecting troll-kind was antiquated and not enough to protect all trolls. While her intentions were far from noble, having one single warrior defend an entire race of magical beings from immeasurable forces actually does seem counterproductive. Even more so, giving one person that kind of authority on the grounds of an object deciding at random who has that authority seems a little iffy too. Turns out that the amulet doesn't choose at random. It's, somehow, Merlin himself who does the choosing. Though the point still stands when it's revealed that Merlin is an emotionally abusive and arbitrary Jerkass. The other issue is that a majority of the trolls (at least in Trollmarket) are pacifists and refuse to fight. Someone needs to protect them.
Claire's mom on learning about the trolls and realizing that there's an apocalypse beneath people's feet wants to warn the mayor. The kids manage to convince her not to because if the masquerade breaks, then the Trollmarket refugees and the humans of Arcadia will be imperiled by this sudden change in status quo, especially with Gunmar on the way and humans lacking the necessary firepower. While they have a point, she also brings up the good point that the mayor has a duty to protect the city, and the people of Arcadia should know they're in danger. It also doesn't help that some trolls have been eating people's cats, and Glug was also accused of Sticky Fingers in an earlier episode.
They Wasted a Perfectly Good Character: Eli is the first person to see the trolls, only for everyone to go Cassandra Truth shortly before Jim encounters the trolls at his house. He and Jim are friends, and Jim saves him from Steve. Yet Toby deliberately deletes evidence that Eli has of the goblins, and pretty much shut him out. He could be an interesting contrast. This is thankfully rectified in Season 2 onwards.
Jim and Strickler are established in the first two episodes as having a fairly close student and teacher relationship; Jim goes to Strickler for advice, and Stickler has a pet name for him, 'Young Atlas'. You would think that there would be more conflict between Strickler's Changeling duties and his regard for a boy he seems to genuinely care for; however, once the premiere is over, the series makes little to no use of this connection until episode 10, when Bular reveals Strickler's true identity to Jim. Bular and Gunmar's intention to test Strickler's loyalties thus comes rather out of nowhere, since he's shown no concern or hesitation over Jim before now. Downplayed in that Strickler keeps Bular from attacking a detransformed Jim and his mother at their house by citing Pragmatic Villainy, helps bail him out of jail by "persuading" Ms. Nomura to not press charges for Jim and Toby breaking into the museum, and is horrified that Bular sent an assassin to kill Jim on his birthday. He doesn't have the courage to directly spare Jim, since his first loyalty has to be to the Gumm-Gumms, and thus he comes off as going halfway.
Morgana is revealed to be the actual Big Bad of the show, and driving force behind most of its events, and we learn basically nothing about her or her motives. Instead of exploring her and Merlin's past in the form of a flashback episode, her relationship with him, what she was like as an apprentice, or why she betrayed him and allied with the Gumm-Gumms to bring about eternal night, all we really learn is that she's evil and extremely powerful. Even Merlin himself doesn't reveal much information, other than the nature of their relationship. This could be mitigated somewhat if the future Tales of Arcadia installment, Wizards (a fantasy-based series taking place in the same universe) expands upon Morgana's past, but as of now, whether the topic will come up is unknown.
The Fantastic Racism that Changelings suffer becomes much more interesting when Nomura and Strickler, the two Changeling characters who are given the most screen time, both each pull a HeelFace Turn, and become allies of the main characters. One would think this issue might come up in another episode as a result, perhaps one involving the trolls of Trollmarket learning the error of their ways and deciding not to judge Changelings before they get to know them. Unfortunately, it isn't given any more screentime. There's also the implication that, when Not-Enrique brought the human children over from the Darklands, many of the changelings on Earth may have been forcibly transformed into their troll selves in front of completely unaware humans with no warning. Granted, the series ending very soon after the final battle means that any discussion of these plots would have to be covered in one of the two upcoming series, and could still potentially happen.
A tiny one: After getting let in on the masquerade, Claire's mom wants to tell the mayor about the troll refugees and Gunmar. The kids obviously shoot that one down because the trolls don't want the masquerade to break when they're already on the run from the Gumm-Gumms. Still, it might have been interesting to see an integration between the two societies, with maybe the town providing more permanent and sun-proof digs for the trolls.
The Woobie: Many of the characters get put through the wringer.
Jim had a relatively normal life, even though his father abandoned him and his mother is overworked. Then, when his life as the new Trollhunter starts, he's stressed and even gets into intense fights with his mother. By the end of the series, he's forced to almost completely abandon his human life altogether.
Barbara — her husband up and abandoned her for his girlfriend. She's overworked as a doctor and completely unaware of her son's double life, constantly worrying over his increasing lies, disappearances, and bruises from his fights. Then the man she's dating uses her as a pawn against her son by binding his soul to hers, so that if Strickler gets injured then she gets injured, and vice-versa. It's a small wonder Barbara breaks up with him before her memory gets wiped from the spell's reversal.
Toby — His parents died when he was very young, leaving him to live with his grandmother. He became more unsure of himself on the team in "Airheads". And after bonding with Aaarrrgghh!! the whole season, he witnessed his friend be killed by Angor Rot.
Claire — Finding out that her little brother was kidnapped and is now in the Darklands did a real number on her, as shown when her greatest nightmare was not being able to find Enrique and blaming herself for what happened, not to mention being enslaved by Morgana during season three.
Draal, due to being the previous Trollhunter's son. He reveals that his father Kanjigar would be cold with him, and Kanjigar's ghost admits it's because I Work Alone and Trollhunters risk their loved one's lives every time they fight. When Draal challenges Jim, and then engages in a rematch, he's humiliated by Jim sparing him and has to leave Trollmarket for a while. Then he vows to repay his debt to Jim by protecting Barbara and serving as one of Jim's trainers, since he knows what it's like to lose a parent. To be welcomed back to Trollmarket, he had to lose an arm to stop the bridge from forming. He's also not surprised when Jim tries to lie to him about his father missing him. It gets worse when Merlin reveals that in an alternate timeline where he became the Trollhunter, he died due to lacking Jim's circle of friends.