All Love Is Unrequited: Played with, Katara and Zuko do have feelings for each other but are afraid to admit it. Played straight with Mai and Jet who have feelings for Zuko and Aang who has feelings for Katara.
Abandoned Area: There're a lot of abandoned soldier homes all over the Fire Nation. After "The Southern Raiders", the Gaang hides at one at first before going to Ember Island.
Adaptation Expansion: The fanfic expands what happen between episodes, giving the Gaang a longer time to get to know each other.
Betty and Veronica: Played With trope. Mai is the Betty and Katara is the Veronica with their traits switched around: Mai is Zuko's childhood friend, the "safe" choice, and a lady of the court but with Veronica traits like being different to what he's used to (i.e. banishment and traveling), is very wealthy, used to commanding servants and is an Ice Queen. Katara is the Veronica in that she's exotic, seemingly unattainable due to their past history and possible futures, is outside of his world (i.e Fire Nation), seemingly unaware of Zuko's affections, but Katara has Betty traits such as being emotionally reliable, is Zuko's best friend and is part of Zuko's past lifestyle of banishment, chasing the Avatar, traveling and re-banishment.
Big Fancy House: Zuko's vacation home on Ember Island. In fact he used this trope to convince the Gaang to hide there. The Royal Villas are also this, seeing how they used to house the royal family.
Blazing Inferno Hellfire Sauce: Fireflakes are very spicy to Non-Fire Nation, averted with Fire Nation colony cuisine, which A: has evolved to use less spices due to the difficulties in bringing them from the homeland, and B: has absorbed elements of Earth Kingdom cuisine.
Book Burning: Played with by Firelord Sozin, he kept many original documents and scrolls that he raided from invaded areas and burned everyone else's copies. Also, Zhao's burning of the Fire Nation section of the Wa Shi Tong's library is seen while practical is very unusual.
Chekhov's Gun: Iroh's nudity and tea making and Zuko's protectiveness of his uncle. Jet is able to deduce that Zuko's not a firebender, but Iroh is. Zuko's attack on Jet when he deduced this proved his point.
Conscription: the Fire Nation has one with the rich draft dodging and most of the recruits being from the lower classes.
Consolation Backfire: Iroh tries reassure Zuko that his false reputation as a floozy will pass. Iroh tells him that he faced similar accusations himself. Zuko asks how Iroh dealt with it, Iroh said he became a bigger floozy.
Cry into Chest: Zuko ends up comforting Katara this way, although he was very awkward about it at first.
Cultured Badass: Suki, Toph and Zuko can play musical instruments due to their backgrounds.
Cucumber Facial: The spa day that Toph gave to Katara for her birthday had this.
Damned by Faint Praise: Teo says sea prunes aren't the worst thing he ever eaten. Haru says that Teo has eaten grass as a refugee. Teo replies that's what he meant; stewed sea prunes are not as bad as eating grass.
Dark Is Not Evil: Bloodbending helped Katara save Zuko's life after he was electrocuted in the chest.
Defictionalization: In-Universe, after Sokka read about Katara wanting a commonsense stick in her stalker log, he gave her a real commonsense stick.
Deliberate Values Dissonance: Water Tribe patriarchy astounds Zuko and Katara (thanks to her basically growing up with no men around to enforce it), and the Fire Nation judges mental illness with Victorian-esque values which matters when Azula gets institutionalized after her Villainous Breakdown.
Designated Girl Fight: Defied, while Mai and Katara don't like each other and are trying Zuko's affection, they treat each other with civility.
Environmental Symbolism: Katara thinks the rain was in sync with her crying, it stops raining and a rainbow comes out after she lets it all out.
Elephant in the Living Room: the Gaang try to leave Aang ignorant of the consequences of the Siege of the North. Shot down when Arnook gleefully tells Aang of all he had killed by drowning.
Equal-Opportunity Evil: Discussed to why this happened to the Fire Nation: due the extensive war effort more women entered the workforce. Women started to be paid and treated equally when they striked for equal pay, bringing the economy to halt until they gave into their demands.
Fix Fic: A lot stuff is untouched from canon adds stuff behind the scenes like giving Suki a Cool Big Sis personality and character development that she never got in canon. Worldbuilding is added to flesh out the world and the original characters, The Bus Came Back a lot with many minor characters returning. Answers questions the series left unanswered.
Foreign Queasine: Stewed sea prunes disgust Zuko, Haru, Teo and Aang. Zuko finds it incredibly salty and thinks it moves.
Katara describes eating fireflakes like licking the sun. Fire Nation colonial OCs feel the same way with the large amounts of fireflakes in Fire Nation mainland food, as they use far less of it.
Freudian Slip: Zuko introduces Katara to Fat as my Katara. Katara also has her moments.
From the Mouths of Babes: The older members of the Gaang find it funny/mortifying when Toph sings stage!Katara's song, "I Love Willies."
Foregone Conclusion: One for each story, Stalking Zuko: Katara will forgive Zuko and Zuko will gain Katara's trust. Not Stalking Zuko: the Gaang will win the war. Not Stalking Firelord Zuko: Zuko will be crowned Fire Lord and the Gaang will go back to Ba Sing Se. Jet's Troubling Obsession: Jet will captured by the Dai Li and brainwashed.
The Ghost: Mai is not in the first two stories, but her presence still makes a major impact.
Heroes Prefer Swords: Lampshaded by Katara, when Sokka and Zuko teach The Duke swordsmanship with tree branches.
Hero with Bad Publicity: Aang has this with the Fire Nation. It's a Justified Trope; many Fire Nation citizens had relatives that were killed in the Siege of the North when Aang was in the Avatar State.
Hidden Depths: Everyone gets this but props has to go to one-scene characters Ming and Sorrak
Hotter and Sexier: A Boy In The Iceberg's late night show happens to very racy and sexy.
Hypocritical Humor: Katara tries to warn Zuko of him possibly getting stalkers after seeing his Groupie Brigade. Zuko rightly laughs at the irony of Katara warning him.
I Have This Friend: Katara meant this literally with Suki, when trying to explain worrying that a friend is not being careful with her lover. Suki answers her until Katara reveals she thinks her friend might be pregnant. Suki understandably freaks thinking Katara got herself pregnant. Hakoda tried to invoke this trope on Zuko to tell him the possible consequences of hooking up with Katara. It doesn't work because Zuko takes him literally.
In Vino Veritas: Zuko is affectionate and reckless drunk. Sokka is philosophical drunk. Katara gets extremely playful and flirty when Zuko tries to put her to bed. Mai is a shameless drunk.
Insane Troll Logic: Sokka says that since Katara spent three days alone with Zuko looking for the Southern Raiders, she must have had sex with Zuko. Katara turns it on him, however. She says by that logic she should assume Sokka had kinky prison sex with Zuko since he was alone with Zuko for five days.
Logical Weakness: Why did no other firebender prisoner besides Zuko bend heat to keep themselves warm in the cooler? The answer: get cooler fever and now you can't defend yourselves from the guards or other prisoners.
Maid: The OCs found in the Fire Nation palace dungeon after the Agni Kai.
The Medic: As canon Katara but also the OC, Dr. Yang.
Mistaken For Bi: Jet's stalking is mistaken constantly as having an unhealthy crush on Zuko. Jet's friends and therapist tell him that they're okay with his sexuality, just let go of Lee's "rejection" and move on to keep it from taking over his life.
Mistaken for Pregnant: Zuko and Katara feared Suki was this after Sokka told them of dreaming that they were penguins and a Penguin!Suki giving him a bag to lay on. Zuko feared this was a Prophetic Dream.
Moment Killer: Frequently Sokka, but all of the Gaang get a chance to kill a moment.
Never Say That Again: During and after the Southern Raiders, Katara bans Aang from saying the "f-word." It's forgiveness.
Nice Job Breaking It, Hero: Aang doesn't kill Ozai and fulfills his Air Nomad beliefs...Now he completely destabilizes Zuko's legitimacy as Fire Lord and causes a Succession Crisis that nearly tears apart the Fire Nation. As a result no one trusts him to actually take responsibility and fulfill his duty as Avatar.
The Nicknamer: KATARA. Subject for Zuko. Dippy-Flippy for Ty Lee. Gloomy Hairbuns for Mai. Chit Sang is also this. Azula, too.
Padding: In-Universe, the writers of The Boy in the Iceberg don't know what the Gaang nor Azula, Zuko and their friends were doing after Ba Sing Se and the Day of Black Sun so they fill it up with wacky side plots and musical numbers.
Parents as People: Toph's parents wants what's best for her, but clearly don't understand their daughter and hurt her because of it.
The reason Mai's dad quits his job as ambassador of Omashu because he realizes that he missed the entirety of Mai's childhood and neglected her because of it. Mai's mother is a social climber and forced Mai to be prim and proper due to growing up in the Deadly Decadent Court of Fire Lord Azulon and is trying to ensure their survival under Ozai.
Politeness Judo: After Toph falsely claims vegetarianism, Zuko tells Hakoda that he is not a vegetarian, out of fear of insulting him at the Water Tribe feast.
Pragmatic Villainy: Sozin was implied to be this with his large amounts of documents from the Air Nomads, Kyoshi Warriors and Southern Water Tribes.
Quickly Demoted Woman: In-Universe, the Southern Water Tribe Warriors praise Sokka and Aang's accomplishments, but never acknowledge Katara, Suki or Toph's accomplishments. Then they expect Katara to do the sewing and cooking even though the villa has servants. This is used to show how sexist the Water Tribe men are.
Race Fetish: Ty Lee and other Fire Nation women have ones for Water Tribe men.
The Rant: The author's notes offers insight to the writing process, why characters act within fic, why certain cultural influences pop up and show the questions that the author had for canon
Red Baron: The Fire Nation's nickname for Hakoda is "the Blue Wolf".
Real Dreams Are Weirder: Sokka gets dreams of being a penguin and laying on a bag of fireflakes given to him by penguin Suki. Katara gets dreams of Master Pakku in Ba Sing Se showgirl outfit.
Real Women Never Wear Dresses: Subverted, for the author, being feminine doesn't mean anti-feminist. What's bad is when someone is shoe-horned into a role just because of their gender.
Deconstructed, in that Katara was willing to learn healing but didn't want to because she was not allowed to be anything beyond healer. She learns healing of her own accord and because she needs to, and then decides to train to become a doctor now that her warrior-bender skills won't be needed any more (she hopes).
In the Ember Island play, Stage Katara and Stage Zuko
Ty Lee is a somewhat more PG-rated version; the author's notes even say that one possible way that Aang might get her to accept that she's an Air Nomad by blood and is likely an unrealised airbender is by getting her to think that following Air Nomad philosophy — in particular the part about "Free Love" — will allow her the perfect excuse to sleep with every guy she wants without ever committing to any one boy in particular.
Reality Ensues: When Zuko is hit by lighting, he had to see a real doctor and was comatose for a few days and bedridden for a week afterwards. The whole fic has reality ensuing.
Twice more in Jet's Troubling Obsession, when Zuko tries to show Jin the view of Ba Sing Se, she lacks the fitness and strength that most of the Avatar cast has and had to be assisted by Zuko to get on the roof. This was supposed to compare the cast to normal people.
Also, Jet's therapy proves counterproductive because he doesn't believe he has a problem.
Reality Is Unrealistic: Noted by the author when she did the research but had to go with the tropes because the actual treatments would have been too modern for the Avatar verse
Reign of Terror: Ozai had one, which is why most of the Fire Nation accept Zuko. Everybody with their head screwed on right figures he simply can not be as bad as his father was. The only ones to actively seek to enthrone one of the others are either direct profiteers from Ozai's reign or convinced they can "work around" Azula's psychosis.
Right for the Wrong Reasons: The Running Gag of Jet's Troubling Obsession, which ends up being Played for Drama in the final chapter when Jet realizes that while he never found proof for Zuko being a firebender, he saw many instances where Iroh was firebending. He realizes that Iroh was able to stay warm in their poor insulated apartment naked in early spring and is making large quantities of tea without firewood.
Royally Screwed Up: The Fire Nation has a long history of them, besides Ozai and Azula, there was a Fire Lady who only spoke to pineapples and required all of her courtiers to carry a pineapple so she could address the pineapple when she wanted to speak to the courtier.
Rule of Symbolism: Zuko's Fire Lord robes are too heavy and uncomfortable and Azula's pink hospital gown makes her look like a child
The Shrink: Dr. Wang is type 3, but ends up being type 2 to Jet. Dr. Wang is able to pinpoint what Jet's problem is but Jet doesn't want to believe it.
Shown Their Work/Word of God: Every chapter ends with a long, rambly author's note explaining her thoughts on the subjects covered in the chapter and her interpretation of the related canon information.
Stalker Without A Crush: Katara was initially this to Zuko, to keep a lookout for his betrayal. Jet claims he's this to Zuko, and gives every sign of consciously believing his own hype (subconsciously, though, is another matter).
Stay in the Kitchen: Katara gets hit with this trope hard after Sozin's Comet when she reunites with the Southern Water Tribe Warriors. They don't even acknowledge her successes and immediately try to make her do the sewing and washing because she's there.
Team Chef: Lampshaded by Katara, she is only one in their group that can cook.
Therapy Backfire: Zuko and Smellerbee try to get Jet into therapy to for his obsession. Doctor Wang pushes Jet into a revelation, but not one they want.
There Are No Therapists: Averted twice with Azula who gets medical help and psychiatric from Dr. Yang, and Jet who is forced by Smellerbee into therapy with Dr. Wang.
There are no true therapists in the Fire Nation, in the Earth Kingdom however...
Thou Shall Not Kill: Deconstructed in that Aang's decision to spare Ozai's life and take away his bending goes against everyone's (including the past Avatar's) advice, infuriates everyone, and causes dire problems for Zuko's legitimacy as Fire Lord, which is seriously destabilizing the Fire Nation.
Through His Stomach: Hakoda and Sokka believe in this trope when Katara gives Zuko food. Suki tries this with Sokka but turns out to be a Lethal Chef due to lack of experience.
Throw the Dog a Bone: Iroh giving Katara the respect she deserves by calling her Master Katara and acknowledging what she has done for the war. Also, Iroh stealing Piando's gift to Sokka to not shaft Sokka for not being a bender.
Torture Cellar: Ozai has one, and it is used as proof as why he shouldn't be Fire Lord — as much for the illegality of it as for the obvious signs of psychosis.
Too Soon: In-Universe, Katara did not like Zuko joking that he'd rather get hit by lighting than do something else, once he was on the mends
Traveling at the Speed of Plot: Lampshaded in-universe and in the Author's notes. To get the Fire Nation from the Earth Kingdom, Zuko and Katara had to take a shortcut through an ocean instead of their regular route which would take days.
Trilogy Creep: Has three parts with Stalking Zuko, Not Stalking Zuko and Not Stalking Firelord Zuko. To say nothing of the side stories that reveal things like Ursa having been Toph's nanny or the assorted oneshots.
Tsundere: Katara is Type A. Justified, as Zuko was formerly their enemy and Katara doesn't trust him to not betray them. Katara is initially very hostile to Zuko until they become friends and Katara realizes her feelings for him. Then she is no longer this trope when she is crushing on him. Slightly deconstructed when Zuko gets worn out by her hostility and believes them not to be friends
Deconstructed with Jet; he is in denial about his feelings for Zuko, as he refuses to accept he's bisexual, and justifies his stalking as trying to out him as a firebender as opposed to rather creepy lust spawned by Zuko's rejection of him. Zuko, Smellerbee and Longshot believe him to have serious problems, it prevents Jet from moving on or help his friends, and ultimately ends with the canonical events that lead to Jet getting arrested and brainwashed by the Dai Li.
Villain with Good Publicity: Subverted with Ozai; Fire Nation colonials don't trust him, and Fire Nation old guard and the elite generally think Ozai's completely nuts. The only ones who still want him on the throne are those who directly profited from Ozai's being there, or just consider him a "better quantity" than either the now-psychotic Azula or the unknown element Zuko.
We Were Rehearsing A Play: Jet and Zuko say they were acting out the fight scene in the Tragedy of Oma and Shu, not getting into a street fight, in an effort to avoid jail time.
Wham Episode: Aang disappearing before the comet, the Gaang were freaking and thinking that Aang might have abandoned them.
What Could Have Been: Katara's Character Arc of her training to become a doctor was going to address dealing post war racism, the author decided to abort the arc because she couldn't write it with the delicacy and tact the issue deserved.
What Measure Is a Mook?: In-Universe, the Siege of the North killed off many Fire Nation naval soldiers, a lot of them from Ember Islands. The Gaang, excluding Aang and Zuko, didn't realize the human cost until seeing a memorial service on Ember Island for the naval soldiers lost in the Siege. Aang is ignorant of the consequences of the Siege of the North until later on, while Zuko saw the dead bodies while floating on a raft at sea.
What Happened To Appa: Word of God wondered where Appa went during the Agni Kai, but justified that Katara and Zuko must have put him somewhere far away from the site since he's afraid of fire.
What Happened To Hawky Averted. per canon Hawky, the messenger hawk Sokka bought did not show up after 'The Runaway'. In Not Stalking Zuko it is revealed taht he returned during the Gaang's stay at Ember Island with a reply and was sent back with a reply to THAT soon after.
What the Hell, Hero?: Katara does NOT accept Aang's lion turtle excuse, she calls him out for abandoning them in their most critical hour.
Everyone calls out on Aang for sparing Ozai and destabilizing the Fire Nation power structure.
You Are Not Alone: It's implied this was what finally convinced Zuko to become Firelord, that Iroh would be helping him rule.
Your Approval Fills Me with Shame: Arnook congratulates Aang for both his sparing Ozai — explicitly because of this causing major political instability amongst the Fire Nation — and for his slaughter of the Fire Nation navy fleet. Aang is not pleased.
Zuko, I Am Your Great-grandfather: Played with and mocked. When Zuko revealed that Avatar Roku was his maternal great-grandfather, Aang realized that would make him Zuko's great-grandfather. Then Aang proceeds in asking his "grandson" for hugs.