Adaptational Badass: Kotohime. In her short canon appearance, she was an insane princess who thought she was a police officer. Now? She's a police officer who was able to arrest Marisa freaking Kirisame. Granted, Kotohime was having a very, very bad day. And she had Yukari helping her.
Ambiguous Innocence: Yuyuko acts rather childlike frequently, not seeming to understand that things like eating Mystia and forcing her to remain alive throughout entire process are wrong. Her Obfuscating Stupidity makes this even more ambiguous.
Complete Monster: In-universe, Kazami Yuuka is treated as such - her very name frightens and disgusts people. Yukari states this reputation is well-deserved, since she used to destroy villages on a whim and it's very heavily implied she rapes and tortures people that wind up in the Garden of the Sun. And it may be because of something else about her...
Continuity Nod: Chapter 24 has one to A Very Nineball Christmas. When Yuuka takes Team Nineball to her mansion, Daiyousei's snowglobe is among their possessions that Yuuka has brought over.
Cool Sword: Reisen eventually finds Ex-Rumia's sword. It's described as obsidian black, with nasty-looking blades sticking out of everywhere.
Most of Gensokyo'spowerhouses join together near the beginning of the story to take down Rin Satsuki. It doesn't end well.
Satori literally gets curbstomped by Yuuka during Yukari's attempt to permanently get rid of her.
Cute and Psycho: Yuuka smiles almost constantly, and most of the time is almost pleasant to be around. Then she kills people because they happened to be in the wrong place at the wrong time, were in her way, or just to make a point. She used to be a lot worse about this: Yukari said she'd murder whole villages because she'd think it'd be funny.
Deader than Dead: The Kirin have access to a way of killing youkai and faeries and keeping them dead. They did this to Rin's biological parents as punishment for the scandal and treachery they performed.
Yukari is also capable of this, by crushing a being's 'essence'. This causes the target to be incapable of reforming its body. Yuuka walks it off.
Deadly Doctor: Eirin, though supplementing her very weaponizable medical know-how with More Dakka.
Disproportionate Retribution/Wicked Cultured: Yuuka, despite everyone in-universe saying she's unpredictable, has a method to her madness. She only lashes out when someone breaks etiquette. An example being when she killed the couple in the hotel room, because they screamed in terror upon seeing her instead of giving her a proper greeting. Another example being that she didn't attack any of Yukari's backup teams until they attacked her, thus breaking the rules of her engagement with Yukari.
The Dreaded: Nearly everyone reacts to the news that Yuuka is becoming involved with abject horror at the possibility. Their reactions are entirely justified.
Dumb Is Good: Utsuho, very childlike and naive but also the only character to befriend Flandre, and go offer condolences to Remilia (who had been rather abrasive towards her) after Flandre's death/capture.
Dysfunction Junction: Nearly everyone is messed up. Thankfully, we have some persons like Reimu.
Eldritch Abomination: Yuuka is a (former?) Outer God, and her true form seems to be a flower described by H. P. Lovecraft out in space, going everywhere. Satori saw it, which caused her to blank out. Later, Yuuka explains to a guest that what Satori actually saw was but a watered-down version of Yuuka's true horrific visage, and at the height of her power, she was even nastier.
Eloquent In Her Native Tongue: Whereas the Kappa normally speak with an accent appearing to be a bizarre fusion of Jamaican and Dutch, the conversation between Sanae and Nitori in the Kappa's language displays a ridiculous level of articulation.
Fantastic Racism: Nearly every denizen of the Human Village has this with youkais. They shun Reimu despite her being one of their few protectors because she's friends with youkai (as opposed to, in Touhou, simply not acknowledging her efforts). They shun the GPF despite them being the first organised law enforcement agency in Gensokyo's history because they also protect youkai. And Master Sonozika outright hates youkai, especially Yukari, and anyone who associates with them under a fairly standard "all youkai are the same" mentality.
Forbidden Zone: The Garden of the Sun (which, in canon, is populated by fairies who help the garden grow by pointing them towards the sun) and a city that was nuked to Hell and back by Yukari are considered like this.
Foregone Conclusion: The plan to kill Yuuka is being told by Yuuka herself. This is being told after the actual attempt itself.
Gambit Pileup: Everyone wants to use the Shadow Youkai to their advantage, or destroy it, or somehow save face in front of everyone else. Just try to count all the different plots, gambits, and motives running in this story. And it's not over yet.
Glowing Eyes of Doom: Subverted. Rin Satsuki had these when she was trying to make amends, after having swallowed up the wrong person.
Grey and Gray Morality: Many sides have justifiable reasons to intervene in the conflict. Some reasons are more justifiable than others. Discussed by Reisen in Chapter 37.
Gray and Black Morality: When everyone's not trying to stab each other in the back, there's always Ex-Rumia and Yuuka.
Most of what Eirin has done as seen by herself. The Hourai Elixer wasn't supposed to give complete immortality, but make the user immune to disease and age. A defense program that she was involved in while still on the moon created a nearly indestructable monster that got loose and breeds too fast for it to be wiped out completely. Kaguya, upon drinking the Hourai Elixer, was supposed to bring fame and fortune to both herself and Eirin, but instead was disowned and banished to Earth because if it. Rin Satsuki is just the latest on a long list.
The Hero: Reimu, The Lazy Ace, fills this role: she assembles her team with diplomacy, and strive for a better world with heroic means. Of course, it's doesn't mean that she is the only protagonist.
Humongous Mecha: Two of them—the Asakura sisters' Scuttler and Nitori's refurbished Hisentensoku—battle it out for the rights to capture Rin. It ends in a draw—piledriving the Scuttler caused too much wear to the Hisentensoku's legs.
Idiot Ball: Reimu gets the bright idea that she can talk Rin Satsuki into compliance, or at least more willing to accept help. Rin Satsuki's paranoia and madness, unfortunately, just make things worse, forcing Mima to save Reimu. TakerFoxx openly admits that he's doesn't usually like this Trope unless they are well written.
The reason why Yuuka joined the fray, combined with Worthy Opponent and thinly-veiled lust for Team Nineball.
Mima's justification for helping in Reimu. Interestingly enough, the "it" in question is not Rin Satsuki, as was initially apparent, but rather Reisen's ability to act as an Unwitting Instigator of Doom.
The four chapters of The Storm are basically a simple situation —a battle— which rapidly degrades. The results and the full implications of this battle are downright impressive: Satori was mind raped, killed by Yuuka and sealed in her team's crystal, Flandre was mentally tormented by Yuuka before being killed and sealed too, Sakuya and Remilia are terribly wounded and depressed, Yuuka is an Outer God and she learned about other dimensions, Yukari's soul has been corrupted...
Jerkass: A lot of people took a level in jerkass in this fic.
Mad Scientist Eirin, who constantly treats Reisen like shit, even after fucking up her adopted daughter for minor trivialities, and quickly starts arguments over who's responsible for Ex-Rumia. Reisen calls her out on it at one point.
Journey to the Center of the Mind : Rumia had done this in the Deep Within chapters. Kaguya, Mokou and the Shadow Youkai are doing their own one in IM: Rhapsody of Subconscious Desire.
Kill The Cutie: Subverted, but still a reader punch. Yuuka pierces Flandre's heart with a wood stake. Thanks to Youkai Immortality, there is her essence left. And then, Yuuka seals her.
Knight in Sour Armor: Byakuren knows that her ideals won't be quite achievable, not to mention how the rest of Gensokyo lives, yet, she doesn't renounce her ideals, living by them while accepting reality,however, she is one of the more polite examples.
Ex-Rumia does this to Rumia at the end of the latter's Journey to the Center of the Mind . TakerFoxx admits that this may be seen as a Deus ex Machina, but also goes on to say that it was too soon in the story for Rumia to do much about it.
Laser-Guided Karma: The tarantula youkai who harasses Cirno and gets frozen for it in chapter 4 had previously stolen Daiyousei's money and gotten her kicked out of the Youkai Market in A Very Nineball Christmas. And when he tries to get back at Cirno in chapter 15, Yuuka shows up and casually vaporizes him.
Les Yay: Being a Touhou fanfiction, it's almost required to at least have hints of this, such as Marisa's frequent sex jokes, or Wriggle being mistaken for Mystia's lover, or Rumia admiring Kaguya and Mokou's bodies, or Yuuka's... affection towards Wriggle, or the Shadow Youkai threatening to rape Reisen as part of a To the Pain speech.
And how can we forget this phrase Yukari said to Yuyuko:
Yukari(as soon Yuyuko carries her in her arms after the fight with Yuuka): "You…do realize…this doesn't mean…we're going steady."
It's also discussedin-universe. For example, there are some... rumors... about the relationship between Marisa and Alice.
"If anything, [Reimu] hoped that those two would move beyond subtext and make official such a relationship. Threatening to tell Alice whenever Marisa started to get out of line would at least make it easier to control her."
Elly (while fighting Youmu and Yuyuko): "Even in this world, where all rules are lightly enforced, there are certain predator-prey constants. Fire will burn, wolves will prey upon rabbits, scissors will beat paper, and against ghosts, Shinigami will always, always win. It's the circle of life and death."
Originally, Rin can adapt (slowly) to any magical projectile. Then, at the cost of her body, she gains the power of Mega Manning. By absorbing other people in a gruesome way.
When Yukari poisoned the ground to prevent Yuuka from growing plants in the battle field for her to exploit, Yuuka brought them in by useing herself as the carrier. Justified, due to being an Outer God, albet an extremly weakened one.
Eirin, of course. She wanted to do some experiments and studies on her pet's adopted daughter. It created the Blob Monster.
The Asakura Sisters, to a slight degree.
Mima is hinted to be the magical version of this.
Madness Mantra: Rin Satsuki degenerates into this, whenever someone usually Normal!Rumia even suggests that the Shadow Youkai may still be alive.
Madwoman in the Attic: Flandre. While the source material isn't definite as to how it applies to her, in Imperfect Metamorphosis she is this trope all over, introduced singing Sweets Time Midnight while using dead rats as marionettes.
Man Behind the Man: Azrael, or its essence, or its soul, is behind the Shadow Youkai.
Mood Whiplash: Done at the end of chapter one. Done each time we have a silly event in the middle of a serious event.
TakerFoxx admits that when Yuka and Yukari are out of the picture Gensokyo can be a silly place.
Moral Myopia: Yuuka considers Yuyuko's use of psychological attacks against Elly to be unforgivable, but she did the same thing to Flandre. And what Yuuka did was about a thousand times worse.
Nice Job Breaking It, Hero: Yukari calls this on Marisa for stealing the box containing the Blob Monster, and thus unleash the GPF on her. Actually, it's only a method to coerce her.
The Nicknamer: Marisa, calling Youmu "Doubletrouble" or "Bodypillow", Yuyuko "Yugogo", Sanae "Mossy", and more.
Not Now, Kiddo: Yukari commits a truly epic one near the beginning, turning Eirin's objections into the setup for a Pre-Asskicking One-Liner. This does not end well for either.
Offing the Offspring: The Kirin society strictly, strictly controls who gets born when. As in, conception has to go through bureaucracy first. Literally. Rin? She wasn't just born out of misgauging; she was the result of a noble child's affair with a commoner, with the elopement occurring right when an Arranged Marriage was supposed to be finalized. And let's face it—to the Kirin, illegitimate children are a severe abomination. Despite what Reisen might have hoped, because of the layers of Things Meant to Never Happen, not only does Kirin society at large not want Rin back, they want her dead.
Oh Crap: Everyone who faces Ex-Rumia or Yuuka has at least one of these reactions. And on a few occasions hearing the latter's name is enough to provoke one.
One of Us: TakerFoxx. So much that he was delighted when his Fan Fiction got to the Fan Fic Recommendation page. And then got its own page.
One Sided Arm Wrestling: Yuuka was just playing with Ran and, after some talking, lets Ran "win", breaking Ran's arm off in the process. In fact, Ran still obtains what she has came to, but still...
Police Are Useless: Played With. Kotohime and the GPF are kinda serious and 'efficient', in spite of gathering some eccentric characters, but they have to deal with people like Marisa and Yuuka.
Porn Stash: Team Nine at first thinks this is what's inside the crystal box. Later, it turns out Marisa also thought this was how Patchouli would be hiding her porn. In ch. 34, it turns out Sanae has her own stash (whether portraying men, women, or both is not revealed)...or did, until Suwako noticed it.
"It is amazing, the sort of things people will do for love," Yukari murmured. She brought the teacup to her lips and slowly sipped the steaming liquid. "Even the proudest, the most uncontrollable, the most erratic of creatures can be swayed by its power. Mima is no different."
Rape as Drama: It's heavily implied (if not outright stated) Yuuka's raped several people before via placing substances in their tea. Wriggle knows this first-hand, apparently. If that's not enough, Yuuka also briefly plays with the idea of raping Kotohime while the latter is unconscious, only to decide against it when she starts to wake up.
Satan a.k.a Lucifer: Implied to be the leader of the Angels that rebelled. Azrael was implied to be almost as bad as it was, but was too busy with killing everything it could to take control itself.
Science Is Wrong: If you ask Reimu, in any case. And, this being Gensokyo and all, she might be right. Blame Eirin.
Screw This, I'm Outta Here: Lily White, upon seeing how badly the reception to her announcing "IT'S SPRING" as well as the attacks by Ex-Rumia, decides to try again next year, hopefully by then everything will have calmed down.
The Blob Monster was this before being released by Team Nine. Almost an Inverted Trope, because Rin was more of a Sealed Woobie In A Can but was sealed for being dangerous.
The Shadow Youkai is a textbook example. As soon as the story is explained Yukari is forced to defend her decision to "only" seal it.
Sociopathic Hero/Nominal Hero: Mima, not quite having gotten over her Evil Overlord tendencies but still firmly on the heroes' (or, at least, Marisa's) side. Would easily qualify for Token Evil Teammate, except that her side has some other very morally grey characters. Much to Reimu's dismay, Marisa takes after her in this aspect, if her encounter with Kotohime is any indication.
Shoo Out the Clowns: Lily White has decided to get out of there and only come back next year. Cirno's gang appears sporadically, depending where we are on the Sliding Scale of Silliness Versus Seriousness. More they interact with Yuuka, more their apparition are near the Seriousness end.
Despite this trope being in effect, there are still many good jokes to be found in the entirety of the story and its spin-offs, lightening the mood every now and then.
"Maybe one the humanoids? Like Zalgo? No, that doesn't make sense. The Operator? No, that slender fellow's also accounted for. The Rake? Unlikely, but he may know something. Make sure to look him up."
Combined with the witty writing one might sometimes forget this is a dark fic.
Speak of the Devil: Murasa uses this expression when Reimu shows up. Reimu is not amused.
Spotlight-Stealing Squad: Yukari and Yuuka. Even if Yukari is one the main characters and Yuuka a chaotic element who only want to wreck havoc in the story, their interactions and confrontations have taken more and more screentime in the different chapters, cumulating into The Storm. After that, Yukari's soul corruption and Yuuka's injuries will take them out of the story for quite some times, and the plot was refocused on Rin and Rumia.
Straight Man: Youmu takes this role in Chapter 27.
Tarot Troubles: During Rumia's Journey to the Center of the Mind , she runs into Mima, who proceeds to read her past, present, and future, as well as that of several other characters (implied to be Rin, Yukari, Reimu and Reisen) through Tarot Cards.
Rumia is forced to stay within Rin Satsuki and sees every collaboration with her as this.
Reimu is gathering allies to achieve her objective, but these allies don't get along very well.
There's enough animosity between the Ringleaders (especially against Yukari and Mima) to ensure that nothing at all is likely to get done in anything less than an end-of-the-world scenario and even then only with difficulty. Other than Yuyuko, Satori and her own Shikigami almost all of the people Yukari collaborates with at any point have either one or both sides at best thinking ill of the other side. At worst actually betraying each other. And Satori's mostly cooperating for personally pragmatic reasons, to give her and her pets an exemption from being drafted for a task she thinks is worse.
And the crown jewel of the story's Teeth-Clenched Teamwork is the group Yukari drafts to kill Yuuka—one pair is genuinely on her side but is partly there to keep an eye on the least trustworthy combatant, one team is pragmatically cooperating, one team was blackmailed into it and their leader is pissed off at everyone who wasn't, one member was hunted down and offered it as an alternative to prison, then agreed willingly just because she wants to fight, and one member is royally pissed at Yukari and is only there because of another teammate. Fortunately the plan involves very little interaction between the teams and the way it goes Off the Rails involves even less.
There Is No Kill Like Overkill: Eventually subverted. Someone reviewing the "Yuuka assassination team" could say that Yukari is going a little "overkill" when she recruited Flandre Scarlet, Okuu and Yuyuko among others persons of mass destruction, but, know what ? It's not enough. When fighting Yuuka, let's say that a bigWave Motion Gun is the least you must bring. Eventually, the contained power of the Sun itself is not enough for killing her.
Title Drop: A genuine one is done in Chapter 37: All the Right Reasons.
Mima:"Every second she runs free, countless lives teeter on the brink, all thanks to her imperfect metamorphosis!"
"...and don't get me started on your reputation as godlike lovers. It seems that whenever you're brought up, people are either deathly afraid of you or they want you to throw them down and jump their bones. Sometimes both."
Villain Protagonist: Yukari Yakumo is a main character beside Rumia, Rin and Reimu. The "villain" part comes from her conviction that the safety of Gensokyo overrides everything else.
Walking Wasteland: Even touching Ex-Rumia is a risk of death, and is certain death to beings below a certain level of power.
Utsuho, after her Third Leg was broken. Only temporarily, though.
Well-Intentioned Extremist: Yukari, with emphasis on Extreme. Views on exactly how extreme or sympathetic she is varies among readers, but she is certainly capable of some very morally grey acts for (in her mind) the greater good of Gensokyo.
As an example, Yukari pulls a (fully crewed) oil tanker off Earth and blows it up as a weapon against Yuuka.
Worthy Opponent: Yuuka sees Yukari as this and starts harassing her and interfering with her plans, partially out of this and partially because it's amusing to her.
Gambit Roulette: Yukari does this with basically everyone. The author even mentions it himself.
Homage: IM: Rhapsody of Subconscious Desire doesn't only make shout outs. In chapter 4, the group meets Zerg. Yes. Fucking Zerg.
Femme Fatalons: EX-Rumia uses these to horrific effect when separating a rabbit guard and his face.
Foot Focus: Noticeably, all three main characters go barefoot through the majority of the story.
Good Thing You Can Heal: The maiming and regenerating of our immortal protagonists simply does not end, and they're so entirely used to it that they don't even care (many minor injuries aren't even noticed until they physically impede whatever the victim was doing). The one with the least regenerative power suffers the least injury, however.
Remembered I Could Fly: In chapter 4, Ex-Rumia and Mokou are going down a steep path, and her companion has to remind Mokou that she doesn't have to descend on foot. Justified in that Mokou's flight had been disabled before, on two separate occasions (in chapters 1 and 2).
She does it again during the very next encounter, much to her embarassment.
Sand Worm: The dreadful velmick is a bioengineered sand worm. A lunar sand worm.
Karma Houdini: Averted. The tarantula youkai who steals Daiyousei's money and has her kicked out of the Youkai Market later harasses Cirno and gets frozen for it in Imperfect Metamorphosis chapter 4. And when he tries to get back at Cirno in Imperfect Metamorphosis chapter 15, Yuuka shows up and casually vaporizes him.