- Even though his life is boring and stable, Jim also craves adventure. He's also under a lot of pressure as a straight A student who cooks for his mother, makes lunch for Toby, and keeps house.
- Strickler's face when he sees the amulet in Jim's bag, and the Ascended Fridge Horror that Jim was about to confide in him about the trolls. Even though he's later revealed to be a Bitch in Sheep's Clothing, you can tell he wishes that it hadn't been Jim.
- Eli is the first person to see the monsters. Steve locks him in a locker for talking about it.
Gnome Your Enemy
- We first get the implication that the rogue gnome is lonely instead of malicious when Jim sees him trying to interact with the skeletal remains of another gnome.
- It's Played for Laughs, but Toby talking about his guilt over his cat's death is pretty sad.
Win, Lose, Or Draal
- On learning his fight will be a Duel to the Death, Jim leaves messages for everyone he loves, telling Claire the truth about why he's been blowing off rehearsals. Of course she thinks that he's being metaphorical.
- He may have been a jerk before, but you immediately feel bad for Draal after Jim defeats him and he walks away in disgrace with the other Trolls booing him.
To Catch a Changeling
- Jim lets Draal try out the sword. Draal wields it rather excitedly for a brief moment, but since only a Trollhunters may wield the sword, it disappears from his grasp. You can see the disappointment in his face. Draal even briefly sees Kanjigar, his father, in place of his own reflection, taking him back, adding to the pain.
The Battle of the Two Bridges
- Jim and Barbara's conversation at the hospital, where Barbara all but begs Jim to explain what's been going on, and Jim's unwilling to tell her. Given how close they've been established to be, it's painful to watch. It's even worse when you know that from his concussion, Barbara would know that Jim was attacked, and he could have said he was mugged, which is more plausible.
- Just before Jim leaves to hand himself over to Strickler, he tells Draal he hopes he is the next Trollhunter if anything happens to him. Draal's quick to reply that he hopes it doesn't come to that.
Return of the Trollhunter
- Claire promising Enrique through the re-destroyed Killahead Bridge she'll rescue him.
- Kanjigar revealing that due to the danger of his work, he was forced to push his son away, and largely leave him out of his life for his own safety. He expresses his disappointment that Jim failed to do so.
The Shattered King
- Toby saying goodbye to Sweet Wumpa.
It's About Time
- Angor Rot's origin story and his unintentional destruction of his own soul.
- Aaarrrgghh saying goodbye to everyone before he rejoins the Krubera, but Toby can't bring himself to say his farewell. Luckily, Aaarrrgghh ends up staying.
A Night To Remember
- When they are prepared to do the incantation to stop Strickler and Barbara's souls from being bound, one of the conditions, being that Barbara will forget everything that's happened (including that Jim is the Trollhunter) he attempts to apologize before she cuts him off, saying that she's looking forward to forgetting him. Did he deserve that after all the crap he's done? Yes. Did it still hurt since he genuinely cares for her? Yes.
Something Rotten This Way Comes
- Strickler saying goodbye to Jim, and giving him the last Triumbric Stone. He decides to leave Arcadia since Barbara broke up with him, Jim admits that Trollmarket can't trust him, and he's been kicked out of the Janus Order.
- Aaarrrgghh performing a Heroic Sacrifice to save Toby.
- What makes it even more hard to watch is Toby's immediate reaction is to kill Angor Rot. His voice is just in so much pain.
- Draal seeing the spirit of Kanjigar, his father, who tells his son he is sorry for pushing him away.
- No one tells Barbara that Jim is in the Darklands. Instead, Toby poses as Jim using a glamour mask to not worry her, and they claim Jim is sick at school.
- Jim while surviving in the Darklands makes chalk drawings of his friends and talks to them.
Grand Theft Otto
- Look at Gunmar's face really closely when he's announcing his plans to corrupt Jim. The way that his face is animated as he's talking about Bular perfectly conveys someone who not only grieves for a loved one, but looks as if he's in complete denial; like he can't believe his son is actually gone.
- When Aarrrgghh is brought back to life, he freaks out and is flailing at everyone. Then he remembers that Toby is his Wingman, and calms down. Then he learns Jim went into the Darklands alone because of his Heroic Sacrifice, and his face looks crushed.
- Draal hugs Kanjigar-possessing Aarrrggh, who in turn is more affectionate to his son. They only have limited time, however, because Kanjigar needs to power the bridge.
- Blinky on learning that his brother is not dead, but serving Gunmar, refuses to believe it. He tries to convince himself that Gunmar brainwashed Dictatious into serving him. Dictatious cruelly tells him that he's Not Brainwashed and serving Gunmar willingly. Then tortures him and manages to deduce the location of Killahead bridge. Ouch.
- The cat that the goblins catch and eat in the opening looks a lot like Claire's cat, seen in previous episodes.
Just Add Water
- We finally find out what happened to Toby's parents; they went on a worldwide cruise to celebrate winning the lottery, and the ship was destroyed in a storm. He was two years old at the time.
- Jim admits that he doesn't know what being a father would be like since his own father left a long time ago, and Strickler, the only other candidate, ended up being evil. He doesn't even consider Blinky since well, Blinky is a troll and his teacher.
- When Steve wants to ask Eli about monsters, Eli is convinced that Steve wants to shove him into a locker and saves him the trouble by climbing into the locker and shutting the door.
- Eli's Heroic BSoD when Steve shares the theory that Jim is an "evil creep". He's very relieved to find out that he and Steve were wrong.
The Reckless Club
- Draal may not wear the amulet, but he has the Trollhunter fighting spirit. Too bad this mean he loses to Gunmar, believing himself responsible for abandoning his post, and fights him to the end, announcing he is Jim's protector. Gunmar then hits him with the brainwashing sword, rather than killing him.
- Steve gets a tiny Reformed, but Rejected moment when he asks the other detention classmates why they can't believe he could be a good guy. No one answers. They're right, but it still hurts.
- Jim refuses to fight a brainwashed Draal, and he begs for his friend to return. Then Gunmar says, speaking through Draal, that his friend is "gone".
- Jim's Heroic BSoD when he's locked in a cage and weighed down with how his actions have hurt people.
- All of the hints that the alternative timeline is a dream/illusion and thus a Secret Test of Character for Jim from Merlin to encourage him to not give up the amulet:
- He doesn't audition for Romeo and Juliet despite knowing that it's how he and Claire bonded initially. This leads to Steve getting the part. (Which makes no sense, because Steve only joined the cast in the original timeline to take the role from Jim, but in the alternate timeline, Jim isn't in the cast and he and Steve never had the fight leading to Steve's public humiliation and broken tooth and vow of revenge.)
- He hasn't done the training, but his body is still athletic and knows how to fight, while he practices alone.
- Strickler believes Jim almost immediately and pulls a HeelFace Turn when he realizes that Jim is right and that Gunmar will turn on the changelings. He then fights Bular and Gunmar when they corner him to buy time for Jim to get to the Museum and the Amulet. Strickler did no such thing in canon until he had lost everything.
- Nomura and the goblins fail to see Jim in the museum, even when they pass right in front of him.
- Killahead Bridge still has an open portal to the Darklands while the Amulet is destroyed on the floor in front of it, even though removing the Amulet from the Bridge has previously been demonstrated to shut the portal down.
- The fact that at the end of the episode Jim returning to the original timeline, where he's being accused of treason against trolls, is the better outcome than being wiped out in the alternative timeline. Even when trying to make things right he can't catch a break.
Mistrial and Error
- Vendel being killed by Usurna.
In the Hall of the Gumm-Gumm King
- Gunmar brutally massacres the Janus Order which has spent all their time trying to bring him back to the surface world. They might've been villains, but they deserved better than to be betrayed by the one they served.
- Draal performs a Heroic Sacrifice in fighting the newly-resurrected Angor Rot, and reminding Jim that he fulfilled his promise to protect him. And in a really sad moment of Book-Ends, he crosses his arms just like his father did at the beginning.
A House Divided
- Jim's flashbacks to the events of the series- his friendships, his triumphs, his losses- so he'll know exactly what he's losing before making the decision to abandon his human form (and by extension, his normal life) to gain the power he needs to save Arcadia from Gunmar and Morgana- by becoming a human/troll hybrid permanently. His friends and family are pleading with him not to do it, but Jim just stoically armors up and accepts it as the price to pay. In all the ways that matter, Jim's childhood is over.
- It's an even greater gut-punch when you look at the others' reactions. Barbara begging him to come out, Strickler insisting there are other ways, Jim's momentary pause at Claire's pleading before going through with his plan..., the whole scene plays out like Jim is about to commit suicide - which, in a sense, he does.
- Jims complete mental breakdown after he chooses to be turned into a Half-Human Hybrid permanently to better fight Gunmar and Morgana.He's fine with it for a bit (doing things like playfighting with Aaarrrgghh!!! and outpacing Claire in a treetop chase) until the drawbacks eventually start hitting him- he comes across a stream in the woods where he gets a good look at himself and encounters trolls who recognize him as one of their own, even as he tries to explain he's human. Then, as the sun rises, he realizes he can't be in sunlight without getting hurt. Later that night, when he tries to eat dinner with his mother like nothing's changed, he finds he can't eat human food- instead eating a blender and other miscellaneous items. When Jim then goes up to his room to try and think, he finds he can't take the Amulet off. He starts trashing his room in frustration, comes across his high school yearbook- and realizes he'll never even graduate high school because of the choice he's made. In his breakdown, Jim runs off to the school to sit at his old desk while remembering his pre-Trollhunter life, sadly carving his name into it, and then gives in to his more animalistic side when Toby and Claire manage to find him, saying that the Jim they knew was gone. The rest of the Trollhunters manage to talk him down and remind him that he's still himself inside, and they'll still be there for him.
- Although this is downplayed by series writer Aaron Waltke saying on Tumblr that he couldn't remove the Amulet because of emotional turmoil and it was trying to protect him.
- Jim's response to his mother when she tries to tell him everyone's there for him:Jim: I can't live in your world anymore. I can't be in the daylight, I can't eat dinner...
The Eternal Knight
- The final scene of the series as after the battle, Jim has to abandon his human life and leaving his mother and best friend behind, not to mention that he will unlikely return back to being human after becoming a troll-human hybrid, by going with Claire and the rest of trolls (which includes Blinky and Normura, barring Strickler and AAARRRGGHH!!!, who decide to remain at Arcadia) on a journey to New Jersey with Merlin to start a new Trollmarket there, but it's more sweet than bitter in terms of being a Bittersweet Ending as Jim and Claire tell Toby that they'll see him again.
- After two more episodes of Anton Yelchin as Jim in Season 3, we finally reach the end of the episodes he was able to record before his untimely death. The next episode opens with Jim inhaling gravesand that changes his voice, and it hits you that after a two year reprieve, Yelchin is actually gone from the world forever.
- Archival recording is used so that Yelchin can have the last line in the series.Jim: Destiny is... a gift. Never forget that fear is but the precursor to valor! That to strive and triumph in the face of fear is what it means to be a hero! Don't think... Become.
This series is dedicated to Anton Yelchin