WARNING: tons of spoilers below! Also, these are somewhat snarky. I couldn't help myself. XD
X1: Koushi I
In which... Shirou Kamui returns to Tokyo after 6 years, according to his dead mother's wish. And is generally a bratty prick to everyone he encounters. Eventually he gets himself badly wounded, but Fuuma finds him and takes him home instead of letting him die in the street like a dog.
X2: Koushi II
Fuuma interrupts Yuuto and Sorata's
foreplay battle, thus proving that there is more to him than meets the eye. Kotori's Severed Head stars in Kamui's fever dreams (along with her mother's). Kanoe is a ho, Satsuki is a computer whiz, and Nataku kills Monou Kyouga while stealing the Shinken.
X3: Shichiyou I
In which... Hinoto dreams of TWO kamuis, Kanoe is a ho and Yuuto is her manwhore; Kamui gains an aunt; Arashi meets Aoki; Karen hangs out on top of lamp posts in her underwear; and Fuuma is stoic but has disturbing dreams involving his dismembered mommy and his crucified sister. Said dreams eventually become a wet dream about molesting Kamui.
X4: Shichiyou II
In which... Fuuma continues to be stoic; Sorata hits on Arashi. Hinoto dumps the weight of the world on Kamui's shoulders, and he proceeds to be brat about it; and Kusanagi saves Kotori from being remotely tentacle raped by Satsuki and Beast.
X5: Shichiyou III
In which... Yuzuriha is genki and Inuki invisible; Hinoto's basement headquarters is attacked and the Seals start earning their keep; Kotori likes birds; Kamui considers giving heterosexuality a shot; Karen is comfortable with her half-naked body; and Kamui had a traumatic past.
X6: Shichiyou IV
In which... SEISHIROU SHOWS UP AND IS THE SMEX. And interrupts Kamui's feeble attempts at being heterosexual. Fuuma saves him and Kotori and then forgets himself and molests Kamui. CLAMP attemps to explain what a "genderless bioroid" is. Sorata hits on Arashi some more. Kotori has scary dreams and might possibly be mentally unstable. And Fuuma tries molesting Kamui again, but is interrupted by Tokiko, who gives birth to the 2nd Shinken and goes splat.
X7: Shinken I
In which... Tokiko goes splat some more; "mentally unstable" is not a strong enough description for Kotori's brand of looniness and has visions of her mommy as a mermaid, meets Kakyou, and has more scary dreams. While hugging Tokiko's Dismembered Head. Fuuma continues to confuse Kamui by swinging back and forth between Concerned Old Friend and Handsome Potential Rapist. Seishirou and Subaru make brief cameos and the USTy fanfare of their unresolved issues is heard on the horizon.
X8: Shinken II
Kakyou has a vision of Fuuma taking up the second Shinken and sees that it's his fate to fight Kamui. Yuzuriha makes Daisuke blush. Seishirou and Subaru are reunited after 9 years, and the UST makes buildings explode. The Clamp Campus Detectives take Kamui and company to CLAMP Campus; where Nokoru reveals certain facts to Kamui. Fuuma hits on Kamui some more and is interrupted by Crazy!Kotori falling in a pool. Kamui chooses to be a Seal, Fuuma goes
Dark Kamui, impales Kamui with sharp phallic objects, licks his neck, and stabs his crazy sister with the Shinken.
both kamuis start seeing other people.
In other words: Kamui "goes within" to escape from the horror that his life has become, and manages to confuse Subaru for a seme. Meanwhile, Fuuma finds Kakyou and uses his newfound Power of SexyFuck to break his dreamscape, making it QUITE clear that Kakyou's Seme Is In Da House. Then he carries his newly claimed uke off.
In which... Nokoru has Kamui seal the Shinken at the heart of CLAMP Campus. Fuuma shows up at Kanoe's doorstep with his comatose uke. The rest of the Angels join the party. Kamui goes back to Hinoto in his search for truth and meaning and there finds out that his and Fuuma's mothers were lesbians and in love. He also finds out that Fuuma ALWAYS had a bit of a blood fetish. Kakyou hijacks the dreamscape because he can kick Hinoto's yumemi ass with HIS m4d yumemi skLlz, and shows Kamui that there are two side to every story.
X11: Kekkai I
In which... 3 months have passed. Kamui, Yuzuriha, Sorata and Arashi are all living together and attending CLAMP Campus. Arashi is still not putting out. Segawa Keiichi is genki, cute and continually hitting on Kamui, who would rather wallow in his unrequited crush on Subaru. Fuuma is bored by the inactivity and decides to set things in motion. He decides to take down the kekkai at Sunshine 60, but first attacks the lab to get Nataku's life support data first. Kamui arrives at Sunshine 60 to try and save the kekkai. Fuuma explains that it's his job to kill all the Dragons of Heaven and sets about making Kamui his bitch, when Subaru arrives to save Kamui's ass... only to be seriously freaked to find that Fuuma looks like his beloved Seishirou.
X12: Kekkai II
In which... Fuuma pokes out Subaru's eye (but only because it was subaru's wish) and Sunshine 60 falls. Kakyou makes cryptic remarks about the future already being decided as long as people don't abandon their Wish. Subaru and Kamui angst. Fuuma and Seishirou flirt. Keiichi's mother died in the earthquake, but Keiichi will go on living for his parents' sake. Fuuma struts around Tokyo looking cooling in his new Little Glasses of Sexy Fuck. Yuzuriha is awed by Fuuma's smexiness on the way to her ice cream date with Kusanagi. Kusanagi psychoanalyses Fuuma for her. Daisuke and Kamui go visit Nataku's scientist grandpa in the hospital. Satsuki and Beast attack the kekkai at Shinjuku.
Fuuma sits on a ledge and is amused.
X13: Kekkai III
In which... Yuzuriha goes one on one with Satsuki. Satsuki kills Inuki. Kusanagi finds Yuzuriha and takes her to a military hospital. Fuuma reveals that because he is "kamui', he knows EVERYONE's wishes. He kills Daisuke because his wish is to give his life to protect Hinoto. Kamui is pissed. Fuuma overpowers him and molests him, but leaves when Sorata and Arashi arrive. The Shinjuku skyrises fall. Yuuto flirts with Satsuki. Kakyou tells Hinoto that she's a sorry excuse for a yumemi. Karen invites Aoki to her place. He touches her teddy. She drugs him to go play with Nataku and Yuuto, who are taking down the kekkai at the Yamanote train line. Yuuto and Karen flirt. A lot. Aoki shows up and Karen disses Yuuto, because she believes Aoki must be the better catch since he's married. Whatever.
Oh yes. The Yamanote kekkai does NOT fall.
X14: Kekkai IV
In which... Kakyou has bondage dreams about Naked!Kamui. Fuuma is not amused and reminds Kakyou who his seme is. Then he hangs out at Ebisu with a little girl and a stuffed frog on his head. When the girl leaves, he makes the Ebisu kekkai go boom using soda cans as detonators (McGyver much?). Dark Hinoto rises from Hinoto's consciousness and molests her better half. Subaru is a ho and flirts with Kamui. Keiichi is still genki... get a good look, we won't be seeing him anytime soon. Fuuma gives Seishirou a lick of his ice cream while destroying Shibuya. They decide to go partake of all the pleasurable things (sex and crepes) before all of Tokyo is destroyed. Sorata hits on Arashi. Karen and Yuuto want to have sex but don't. Fuuma's infidelity sends Kakyou into a bout of fatalistic angst.
X15: Kekkai V
In which... Kakyou remembers his lost love Hokuto and angsts about her and the relationship they never had. Fuuma senses his uke's angsty vulnerability and takes inmediate action. Kakyou loses himself in his seme's comforting embrace. The webmistress becomes a die-hard FuxKyou fangirl. Also, Yuzuriha tells Kusanagi that she loves him. Fuuma gets Yuzuriha a new puppy.
X16: Kekkai VI
In which... Rainbow Bridge witnesses the climax and end of the Greatest Tragic Gay Love Story Of All Time. Other stuff happens too, but it is insignificant in the face of Seishirou and Subaru's undying gay love.
X17: Shumatsu I
In which... Dark Hinoto is still molesting her better half and Kanoe senses her sister's distress. Kamui proves he's not COMPLETELY useless by finally figuring out that Hinoto Is Ebil. Arashi and Yuzuriha manage to protect a kekkai! Sorata almost dies and finally gets laid. Yuuto flirts with Satsuki and Beast is JEALOUS. Kamui angsts. Fuuma gets off on watching Kamui angst. Kakyou is sad and needs to feel his seme's reassurance. Fuuma obliges him. Hinoto sends Aoki and Karen off to Ginza hoping to get them killed. Last of all, Fuuma hands out used eyeballs to aspiring sakurazukamoris.
In which... Arashi runs away the morning after, which doesn't really speak well of Sorata's performance. Aoki and Karen are the ony Seals that manage to consistently protect ANY kekkai. They spend A LOT of time NOT having an affair, but are interrupted by Nataku developing a personality, complete with ill-fated wish. Said wish is granted by (you guessed it) Fuuma (aka "Daddy"). Then Fuuma goes off to flirt with Sakurazuka!Subaru on a rooftop. I think they're wearing each other's clothes by this point. Most of Tokyo has fallen to the earthquakes. And if you blink, you'll miss seeing the entire city being flooded. I know I did.