* AntiClimaxBoss: Fuuma in the film adaptation is [[spoiler:killed]] rather fast, due to the movie's time constraints.
* BaseBreaker:
** Kamui at first due to being a {{Jerkass}} who avoids contact with anybody. It should be noted that Yuzuriha and Sorata actually understand why he acts like that and Hinoto even reveals that he could actually destroy mankind depending on his development despite her visions of Kamui as messiah figure. Kamui finally becomes more likable when opening up to Kotori.
** Even although most fans prefer the manga and/or anime over the film adaptation, it has its fans due to its grittier, gorgeous animation (some think it is still better than the often OffModel style of the anime), comprised story and emphasis in action (which eliminated the trouble of the KudzuPlot which was quoted as one of the low points of the series) and rotund ending (especially for those who dislike Fuma).
* BrokenBase: About whether the manga will (or should) ever continue or not.
** Given that ''X/1999'' had been put on hold several times until its official hiatus in 2003 due to mirroring RealLife incidents, some people find it [[TooSoon understandable]]; however, Nanase Ohkawa originally mentioned that they would continue the manga when they have a magazine that is willing to publish it, yet it's already been more than a decade and CLAMP have four works in their table (''[[Manga/TsubasaReservoirChronicle Tsubasa World Chronicle]]'', ''[[Manga/{{Xxxholic}} xxxHolic Rei]]'' and ''[[Manga/LegalDrug Drug and Drop]]'', as well as the newer ''Manga/{{Gate7}}'') without news about the series. And after they only moved the schedule to put three of them on hiatus, leaving ''Tsubasa'' as the only running work, ''X/1999'' fans have given up hope that the manga will never return at this point.
** The situation is especially unpleasant having in consideration that most fans of ''X/1999'' were unsatisfied enough with the run of the originals ''Tsubasa'' and ''xxxHolic'' to believe that they don't deserve to receive priority for sequels before ''X'' get a freaking conclusion once for all. However, conversely, considering the mixed reception of the endings of ''Tsubasa'' and ''xxxHolic'', you have some fans who do ''not'' want CLAMP to finish ''X/1999'', thinking that they would only ruin it by following the same ending style.
* CrowningMusicOfAwesome:
** A lot of piano players know about Naoki Sato's sublime LonelyPianoPiece [[http://www.youtube.com/watch?v=MhkxSHsb0xM Sadame]] which is Japanese for "Destiny" which is omnipresent in the anime [[https://www.youtube.com/watch?v=NX6qZlQnb1M in its symphonic version.]]
** [[https://www.youtube.com/watch?v=_W-eEilKDM8 the TV series opening theme]], "ex Dream" by Myuji.
** Hinoto's theme from the anime.
* DarknessInducedAudienceApathy:
** The movie version of ''X/1999'' can be this since this was released while the manga was ongoing. The world is about to end as usual but both ended killing each other and dying at the same time. The Dragons of Earth are portrayed as mass murdering assholes which includes Kusanagi, who is known to be TokenGoodTeammate and a FriendToAllLivingThings. The Dragons of Heaven are still the good guys but they are slowly decimated along with the barriers they're protecting, which resulted to entire city completely destroyed with Tokyo Tower left standing. And in the end, [[spoiler:Kamui is forced to kill Fuuma by beheading him which leaves him the only survivor in the cast]].
** The manga strays into this in the last chapters as well. The Dragons of Heaven are in a losing battle [[spoiler:where Yuzuriha suddenly disappeared, Subaru defected to the Dragons of Earth after inheriting Seishirou's job with the belief that he wanted to help Kamui realize his "true" wish and Arashi became a pawn to Hinoto's evil side who is responsible for the mishaps that the group's experiencing. It also turns out that Kamui's "true wish" is not restoring Fuuma back to his original self]]. It doesn't help that the manga went a decade-long hiatus with a Cliffhanger which drove readers mad. Of course, most readers want CLAMP to continue the story. But due to CLAMP's recent works which have poor endings, some care less about it with the fear that the ending is probably be more depressing than the movie.
* DeaderThanDisco: The manga once used to be the ''HUGE'' giant of CLAMP, their flagship in a time in which their fleet was still not so large as it would become later. However, due to CLAMP's inability to give the series an ending, its popularity faded away over the years until it got past the point of no return, and the series was forgotten by creators and fans alike in favour of hotter prospects like ''Manga/TsubasaReservoirChronicle'' and ''Manga/{{Xxxholic}}''. Nowadays, few people would read it in case it finally received a conclusion, and even fewer would want it to happen so after knowing the fate of the aforementioned two series.
* DieForOurShip: Poor, ''poor'' Kotori.
** And if you cross paths with a Seishirou/Subaru fangirl, ''don't'' mention Kamui. Similarly, saying the name "Subaru" in front of a Fuuma/Kamui fan can be as unwise as mentioning Kotori's.
* DracoInLeatherPants: Fuuma and ''especially'' Seishirou.
* EvilIsSexy: Kanoe is the embodiment of this trope.
** So are Seishirou and Yuuto.
* EpilepticTrees: Oh, all the theories that have run around about Keiichi in CLAMP fandom.
* EnsembleDarkhorse: There are a lot but two most popular are probably the energetic Sorata and the cold yet kindhearted Subaru.
* FanficFuel: They are probably a lot of fanfics which had a lot of ''What If?'' scenarios such as, 'what if Kamui joins the Dragons of Earth instead and Fuuma go to the other side vice-versa'
** Though they are fanfics of Kamui visiting Yuuko's shop, CLAMP made a short comic of it in ''Clamp in Wonderland EX'' in which Mokona jokingly says that the price of Kamui's wish will be the fate of the world and Watanuki scolds him for making Kamui cry. Fuuma appeares later on and declares that he's the only one who can grant his wish; cue the two fighting again much to Watanuki's chagrin.
* FauxSymbolism: A certain scene in TheMovie, in which [[spoiler: Kotori's dreamseer abilities manifest when Kamui sees her inside a room that looks as if it was filled with amniotic liquid, with the girl whispering [[DoesThisRemindYouOfAnything "What is this Kamui? It's inside of me... it's gonna be born soon... I'll give birth to it soon..."]]. Of course this refers to the Shinken, which Fuuma pulls out at the cost of her life in the end.]]
* HoYay: C'mon, it's ''Creator/{{CLAMP}}.'' The most prominent case [[spoiler: Kamui and Fuuma]] is later turned FoeYay, natch. There are other common matchups as well, including Subaru and Kamui (mind penetration and {{Big Brother Mentor}}ship FTW) and Fuuma and Seishirou (mostly for the symmetry, it seems). Seishirou and Subaru are far enough out of subtext and into text that HoYay doesn't really apply anymore.
** [[spoiler:Fuuma]] × Seishirou was teasingly (and gloriously) hinted at when Seishirou [[CrowningMomentOfAwesome defiled the Shibuya 109 building's kekkai with the blood of an innocent, sending it careening into the Shibuya Station, thus breaking both the Shibuya kekkai and the Yamanote kekkai in one fell swoop]], something that the combined efforts of three Dragons of Earth could not achieve - only to watch it burn whilst discussing sampling delicacies from Tokyo's best restaurants before destroying them all.
** [[spoiler:The scene in the anime in which Fuuma carries Kakyou to the Dragons of Earth headquarters]] has, in some circles, become the launcher of a thousand slash fics.
* ItWasHisSled: Fuuma becoming the main antagonist is the first thing you will know upon knowing the work. Even worse, you [[LateArrivalSpoiler can actually discover it by simply checking the cover of a DVD.]]
* MagnificentBastard: Yuto and Seishiro are very good examples of this.
* MemeticMutation: "Yuuto is a PIMP!" "Kanoe is a hoe!".
* MindGameShip: Both Seishirou/Subaru and Fuuma/Kamui qualify.
* MoralEventHorizon: Fuma crosses it [[spoiler: upon murdering his own sister (and VERY bloodily) to set off TheEndOfTheWorldAsWeKnowIt.]]
* {{Narm}}: In the anime, the abundance of OffModel animation can ''seriously'' disrupt the mood.
* TheScrappy: Kotori, because femininity ''and'' not being physically active is an unforgivable flaw [[RealWomenNeverWearDresses according to many fans]].
* ShipToShipCombat: Seishirou/Subaru VS Subaru/Kamui.
* WhatDoYouMeanItsForKids: The series is mistaken for {{Shonen}}[=/=]{{seinen}} when it is {{shoujo}}. This is due to violent content and a dark story.
* WhatDoYouMeanItsNotSymbolic: This is essentially the Gospel According to Nanase Ohkawa. The major alteration from Judeo-Christian eschatology is the dualism, with the two sides evenly matched and only a slim moral advantage on the part of the Dragons of Heaven.
* WhatMeasureIsANonBadass:
** A lot of fans just ''love'' to bash Kotori for being not only an IllGirl YamatoNadeshiko, but for daring to be emotionally and psychologically damaged after [[spoiler:seeing the birth of the second Shinken]].
** Kamui was HOTLY bashed and loathed by fans for daring to cry and angst over his shitty destiny and [[spoiler:the terrible breaking of his, Kotori and Fuuma's bonds]].
** Yuzuriha, as she basically never wins a battle on-screen.
* TheWoobie: Kakyou, Kotori, Subaru, Kamui, [[spoiler:Yuzuriha when Satsuki decides it's time for a very literal KickTheDog moment and kills Inuki]]... a good chunk of the main cast, really. Not so strange when you consider that they're Team Keep Humanity Alive. Among the fandom, Subaru is the undisputed King of Woobieness.
** Kakyou Kuzuki is a Dragon of Earth. Team Kill Humanity to Save the Earth isn't entirely without Woobies, you know? Outside the movie, pretty much everyone is a Woobie or just plain Affable. [[spoiler: Fuuma's theme is granting wishes (read: Killing people who want to die), the Sakurazukamori assassin is a position apparently passed on by death at the hands of the one the current assassin loves (Seishirou killed his mom), Satsuki was used by first a father and then corporate businessmen who want to exploit her. Kusanagi is perhaps the only one on the Dragons of Earth who takes his side (though halfheartedly) because he's a nature-lover. (Oh, and he's ready to BackStab FUUMA to save Yuzuriha.) Nataku hardly has a past at all because he's a clone. That leaves Yuuto, who's incredibly cheerful and friendly who's pretty much in it ForTheLulz, and even then he wasn't fully evil as he has a sister he misses and genuinely cares for ''and'' refuses to take advantage of Satsuki's crush on him when he could've perfectly done so.]]
** [[spoiler: Nataku]]'s case is ambiguous, since he might not have a proper past [[spoiler: since he's a clone]] but in the manga [[spoiler: what's left of the person he was cloned from's memories play a ''very'' important part in his '''very''' spoileriffic and sympathetic death.]] You could even make a case for the anime, as [[spoiler: Fuuma absorbs Nataku's body to heal himself after Sorata almost kills him ''because'' of his Wish and former life's memories, in a sense.]]
** Subaru was a Woobie before X even started, having lost his twin sister [[spoiler: at the hands of their best friend / mutual love interest, Seishiro. Yes, HoYay and FoeYay in a single package.]]
* WTHCastingAgency: In the Spanish dub of the movie, Aleix Estadella as Nataku and Kusanagi was considered an incredibly bizarre cast choice, especially in the second case, as he is known for playing funny bumbling guys and neither of the two is two miles in range to fit this description. He later voiced Sorata in the anime, a much more fitting character, but ''then'' some critized it for supposedly making him sound too silly.