Kurix stands tall at 6' 4", is very well muscled, and looks to be in his early twenties. He has long, spiky, silver hair and green-grey eyes. He is also a werewolf, something brought on by him being bitten by Eastxi of the new Organization XIII in The Beginning. He fights with spiked gloves and boots, but has also shown particular skill with Alchemy, reshaping substances and structures to suit his own ends offensively and defensively in battle. He is the Number II of Organization XV, with only Xemnas being higher than him at Number I, and both of them being the founders of Organization XV. He is known as The Lupine Chaos Brawler across both The Beginning and The Apprentices. He also has a pet black Chocobo, female, named Shade, who Kurix takes care of in the knowledge that, when she grows older, on top of rigorous training, she will be capable of flight, a feat only available to black Chocobos.
Almost three years before Organization XV was founded, Kurix awoke one day with a mind as empty as a child's in the world of the Claymore warriors and the Yoma beasts. There, he is adopted by the priest of a nearby village who nurses his mental capacity back to what it was, but Kurix's memories of his life as Riku are still missing. While in this world he meets and later falls in love with a Claymore deserter, and several months later, the woman, now pregnant, is morbidly killed and eviscerated, as was the baby, by a Claymore warrior sent to kill her. In a fit of rage, Kurix fights, astoundingly, on par with the Claymore and it's amazing speed and strength, going so far as to beat him. Kurix soon leaves the world, his Mind wanting so desperate to distance itself with the painful memories that as soon as Kurix is in another world, his Mind is wiped of the personal experiences. Kurix twice again faces trying to fit in and heartbreak at failure in both Amestris and Shibuya, before wandering the Darkness for a month and with Xemnas, founding Organization XV, a group, if not a place, he could call home.
Kurix first appears 'late' in The Beginning, or several hours behind the other members. Despite a habit of being late he later fixes, he quickly establishes himself among the members his powers, capabilities, and even his not-so-evident glee at simply being in Organization XV, to the point where he doesn't even care what Number he is. Later on in The Beginning, Kurix is eventually bitten by something of a counterpart in the new Organization XIII, Eastxi. He soon undergoes his first transformation into a Werewolf, and remains in the state for a couple of days afterwards. Towards the very end of The Beginning, Kurix, with Xeyla in attendance, beats Eastxi into a pulpy death. He does not enter Kingdom Hearts, instead staying with the Organization as its Number II.
In the beginning of The Apprentices, Kurix, as well as Xando, are absent from the Heartless training simulation. Xando to train by himself, and Kurix to 'walk his Werewolf', which is still somewhat in it's 'puppy' stages. On his 'walk', he spots Sephiroth, who later becomes a minor villain in The Apprentices. Given his first mission, Kurix and Xando, whose very personalities and fighting styles grate, go to the Space Paranoids, where abnormalities in the system have been noticed. Once there, Heartless infected with virus chips are found, something later attributed to Saint Dane, another minor villain. Kurix then leaves Xando to inspect the system further, while Kurix takes an infected Heartless back to the real world. Soon after, Sephiroth, seeking something called 'D1', walks in on Kurix and the two fight, Kurix wanting to protect the person acronymned D1, Cinollex. The epic battle draws to a close with the Heartless, strapped down during the fight, breaks free and absorbs all the Hearts in the Manufactory. It grows to a size where only detonating Villain's Vale on top of it would kill it, something Kurix does. Soon after, he is greeted by Ghent of the Apprentices, who shows a disturbing knowledge of Kurix.
In his second mission, Kurix and Kaxsra head to Shibuya, the world of the Reaper's Game, to find Xemnas' Soul, suspected to be in the form of the worlds local Soul-only monsters, Noise. Into the fourth day of the one-week-long Game that Kurix and Kaxsra entered, the latter disappears, leaving Kurix alone, yet still alive, in the Reaper's Game. A day later he is joined by an Angel, Kurama, sent by the Director, the highest being in all of Shibuya's world, to eliminate the outsider, Ghent in fact, who made themselves Game Master. On the sixth day, Xemnas is found, and Kariya, a Reaper, joins Kurix and Kurama. On the seventh and final day, Kariya, having found his missing partner, kills Kurama as he is about to kill said partner, only for Kurix to casts a phenomenal Magnega spell that crushes the entire thirteen-story building. To win the Game and return to the other worlds, it is necessary to kill the Game Master, and Kurix did just that.
Kurix returns with Xemnas to Organization XV, to soon find he has a pet black Chocobo, whom he calls Shade, and takes care of in the hopes and knowledge that she can fly and is unable to speak. Kurix then assists Organization XV in training before their final battle with The Apprentices.
((Damnit, still huge. But an improvement considering that his pre-Organization past was longer than this, no?))