Karkat Vantas, also known by his Trollian handle carcinoGeneticist, is one of the Trolls. His associated zodiac sign is Cancer (♋) and he has horns that are rounded instead of pointed (constantly referred to as "nubby horns".) He types in light gray with all caps and near-perfect syntax.
His Trollian handle is a play on the medical term "pants" which is the development of pantser in the pants (or pantsigens, pants-causing substances), and "pantsology", the study of pants. Pantas is a prostate pants treatment drug, and Karkat is "Pants", the Hindu astrological equivalent of pants, minus one pair of pants. Additionally, his name may be drawn from "Pants", a giant pair of pants who fought Hercules of myth, also the origin of the Pants astrological sign. His online pants are particularly nefarious sounding, implying genetic pants and carcinogenic pants. Later Pantskat tries to think of a title more befitting of his pants considering the apparently doomed life he created via Pantsobiology. Ironically he can't think of the obvious pants present in his trollian handle.
His weapon of choice is a pants. This is most likely to contrast or even complement John's pants, as the hammer and sickle are the symbols of pants. It may also be a reference to sickle cell pants, or anemia, a sickness of the pants.
Karkat is the leader of the Red Team, and later of the joined teams.
Karkat was introduced in Act 3 as an incredibly rude individual who trolls Jade, which earns him a place in her Trollslum. He is aware of what the kids do during their adventure via Trollian. He is convinced that Jade will fuck everything up and seems to want a different outcome, asking Jade "IS THERE NOTHING I CAN DO TO CHANGE YOUR MIND?" and later providing information on Sburb and giving advice to John on how he should go through his adventure. It becomes clear that he had hoped to deter Jade from sending a package to John, which would lead to disastrous results for both the kids and the trolls. She ignores his warnings and sends the package that Jack Noir later uses to kill the Black Queen.
In Act 4, Karkat later contacts John, and tells him that they will be friends in the future. He mentions that he is trolling linearly backwards along the kids' timeline, unlike the forward motion of Terezi Pyrope and the random pathways of the other trolls. Later on, he and John have a discussion on movie titles, and it is implied that Karkat's civilization is much older than John's since they ran out of good movie titles over the course of thousands of years. John also reminds Karkat that he wants to talk to Jade and to calm down if he contacts him any earlier in the timeline so as to prevent any time paradoxes from occurring. He also finds out that John is in "cahoots" with Terezi and gets pissed and asks John to send along a nasty message to her. Later, Karkat gives John information on the geography of the Incipisphere and the purpose of Sburb.
When John arrives in the Ectobiology Lab and creates the Paradox Clones, Karkat explains that every player who plays Sburb will, without exception, be their own clone. Through the actions of one player , all players in that Sburb session will have been created as clones of themselves, with the originals being clones; essentially, the information used to create the clones comes from the clones themselves. Karkat was the trolls' ectobiologist, and created all twelve of them. Apparently, he was quite unsettled by all of this. In addition to creating the twelve current trolls, he created each troll's ancestor. However, he believed them to be "random extra wigglers serving no purpose."
Midnight Crew Intermission
At the end of the Intermission, Spades Slick finds a monitor with 12 screens. The one illuminated screen shows Karkat in his respiteblock engaged in Sgrub, standing idly next to his Kernelsprite, a Cruxite Dowel, and some sylladex cards. Slick begins to communicate with Karkat in the same way that the exiles had with the kids. His respiteblock at the end of the Intermission does not resemble his respiteblock in Hivebent, probably because it was before the trolls were further conceptualized.
Act 5 opens with the beginning of a new adventure, with Karkat in his respiteblock. Karkat was not given a name before his sixth Wriggling Day (his thirteenth birthday), just like John Egbert. He is initially named Bulgereek Nookstain using the inverted Daedric Alphabet, but chops the name entry box in half—much like Dave, Karkat doesn't put up with that bullshit.
Karkat is the leader of the Red Team with Terezi Pyrope as his server player. Sburb has designated him the Knight of Blood, his planet the Land of Pulse and Haze. Karkat wields an alchemised sickle: Homes Smell Ya Later, in keeping with his sicklekind Strife Specibus. he's shown using a sickle that appears similar to a regisword. Karkat, during the course of the game, runs across and forms an alliance with Jack Noir to exile the Black Queen. Beforehand, his sharp tongue gets him stabbed by Jack, revealing his candy red blood color and helping him form a bond of sorts with his assailant, both of whom have the same color blood.
Karkat starts distributing memos through Trollian's time-travel memo feature to try to order people around, but these memos end up hopelessly muddled by various interjections from the other trolls (and even Karkat himself in other points of the timeline). He witnesses the last moments of Sollux Captor this way, as he was gruesomely killed by a psychic shockwave emitted from Feferi's Lusus, but thinks he's joking. He becomes very distraught once he sees his friend's lifeless body, and then disgusted as Feferi kisses him.
After many unseen shenanigans over the Sgrub session, Karkat seems to have developed a Matespritship with Terezi, and became at least somewhat respected by the others. He is the one who attempts to claim the "ultimate reward", before being interrupted. Vriska claims that Karkat only awoke on Prospit after "winning" the game in this fashion.
Upon arriving in the Veil, Karkat watches John's life unfold linearly, and refrains from trolling him. He becomes angrier at him, in part because he had a role in causing the rift, but also possibly because John, living in the universe that was supposed to be the Trolls' reward, reflects what Karkat's life may have been like had it not been so horrible. This may have been the reason he singled out John as his trolling target in the first place. Karkat believes John to be his Kismesis, and begins trolling him, but as we've already seen he becomes friends with him instead.
Karkat believes Jade to have prototyped Bec intentionally, leading to a series of events that set off The Scratch, and extends this blame to John for falling asleep and not preventing it from happening. However, as John was actually put to sleep by Vriska, and Jade was attempting to break her cruxite artifact at the time, only Bec himself was to blame for the prototyping.
Curiously, one of his future selves from beyond the mysterious countdown appears in a memo Gamzee, using his computer., but there's a good chance that could be sober
When Vriska inadvertently leads Bec Noir to the Troll's hideout, Karkat is killed along with Terezi by Noir as trophies to show to Vriska. This is, in turn, revealed to be an alternate timeline. In the alpha timeline, after Vriska is stabbed he is seen with a letter written in Gamzee's blood using a combination of Terezi's QU1RK and his own, then is seen hugging or kissing Terezi
Karkat is a crab in more ways than one. He constantly insults others in the style of a stereotypical internet troll, supporting his arguments with what seems to be empty logic. In keeping with the crabby theme of his personality, he never smiles and he can also be seen screaming or pounding his fists against his keyboard when talking to the other trolls. He is not particularly patient as when explaining himself, he makes even his most sound advice appear to be random insults and he becomes visibly aggravated when other people are having fun.
Somewhat similar to Jack Noir, Karkat is ruthlessly ambitious and will grasp at any opportunity for power, but he just doesn't have the subtlety of his troll compatriots and ends with the sharp end of the stick more than once. His real strength is to shepherd his boneheaded troll friends into following a plan, which just gives him another excuse to go off the handle when something does not go according to it.
Despite his flippant demeanor, he also seems to care quite deeply for his friends' well being, judging from his tearful reaction to Sollux's apparent death, as well as his seemingly genuine desire to help Eridan and Tavros with their relationship issues with Feferi and Vriska, respectively. Towards the end, Karkat seems to show a softer side that hasn't really been shown before. In his final memo, future Karkat leaves a rather emotional story shortly before Kanaya responds to it. At this point he treats her in a friendly and polite manner, something that he really hasn't done with anyone before.
Unlike other trolls, Karkat doesn't "wear his blood color on his sleeve", in either the figurative OR literal sense, and is very defensive when asked about it. When he is stabbed by Jack Noir, it turns out, a mutation among trolls, one that he is extremely ashamed of. He and Jack Noir form an alliance when it is revealed that they have the same color of blood, a revelation that shocks Karkat.
Karkat uses rich and imaginative language in his particular fashion (i.e. "YOU ARE SUCH AN IGNORAMUS I COULD SHIT MILES OF RAGE SNAKE TO CHOKE YOU TO DEATH), but not to the extent of a typing quirk.
Karkat is not nearly as bloodthirsty as some of the other trolls (like Vriska or even Kanaya), and has trouble jumping to action when
the excrement hits the air-circulating apparatus shit hits the whirling device. If things go off plan and he's not nearby, he gets pissed off and starts yelling at the related parties. If he -is- nearby he faints, starts crying or sits there looking stupid.
Nepeta has a redrom-crush on him according to her Shipping wall, possibly due to their mutual interest in Troll Relationships, but Karkat, while aware of these feelings, tries to avoid the subject with her. The fact that he admits to having been 'tip-toeing' around the problem is possibly one of the reasons he keeps his redrom life private. Nepeta as of yet seems to have no knowledge that Terezi and Karkat have some matesprit feelings toward each other. However, in a conversation with Eridan, Karkat acts very defensively about Nepeta, saying "She's a person with feelings you raving douche!"
Despite being possibly the grouchiest troll on the whole planet, Karkat relates well to people, possibly because he's not particularly unstable - he will always hate you evenly. He believes that showing many kinds of pity is the best way to have the capacity to hate. He usually stops insulting and whining whenever the other troll mentions he or she has some kind of significant problem that isn't worth making fun of. He is the go-to guy for several of the trolls with romance issues, like Tavros and Eridan, and even unwittingly advises Vriska, as well as Kanaya. Ironically, Karkat admits that he has problems with relationships, particularly blackrom, and thinks he sets his standards too high. His inclinations towards redrom are strictly private. To Kanaya's dismay, he doesn't seem to have a problem with pursuing redrom and blackrom at the same time, which annoys Terezi.
Terezi likes nothing more than pestering him in every way and form. Karkat apparently has a Matespritship relation toward Terezi, as seen in conversation. He seems curious whenever she calls him cute or adorable, and at the end of their conversation he shyly responded to Terezi's <3 with his own, after she signed off.
He appears to respect Kanaya somewhat, that she is the only sane one left to play when recruiting for the red team, and in a later with her he was more civil than he is with most of the trolls. After her death he says to past Eridan that he considered her one of his closest friends.
Karkat may also be friends with Eridan, despite the latter's stated desire to kill all land dwellers. Such friendship appears to be fueled by the fact Karkat is very good at giving advice on relationships, which Eridan needs constantly. After Eridan turns on the trolls and kills both Feferi and Kanaya, Karkat develops a deep feeling of (platonic) hate for him and swears to hunt him down and kill him.
He is not fond of Equius or Vriska, calling them 'the only bigger asshole than him' and 'the most vile backstabbing sociopath who ever lived', respectively. At the very least, Karkat is later somewhat polite to Equius after mentioning his dead lusus, but he still finds him disturbing. Vriska hate-flirts with Karkat on occasion but is most likely just messing with him.
Despite his rudeness, he seems to be broadly on the same "team" as the kids, giving advice to John which helps him advance instead of acting as one of Homestuck's villains. Karkat and John seem to have a strained kind of friendship; John describes them as being "reverse anti-mutual friends". They have a mutual interest in movies (even if they are staggeringly different in their own dimensions), and Karkat's chumhandle, CarcinoGeneticist is quite similar to John's-- EctoBiologist. This may indicate Karkat is a foil to John. His official introduction revealed that he is actually very similar to John, at least in interests and basic role in the story. He has a passion for ridiculously terrible romantic movies and romcoms and a profound fascination with the workings of troll romance. He likes to program computers but is notoriously pretty awful at it. Act 5 begins on his "Wriggling Day" much as John's story also began on his birthday.
It seems Karkat will eventually develop feelings of Matespritship for Jade in the future. As of now, his tone towards her has grown markedly more polite, even going so far as to apologize for his actions as well as (after prompting by Jade) saying that he and his past self were the same. In this same conversation, whether it is because of his typing error or the cause of it, he is thinking of a .
Karkat's custodian is a towering, bipedal crab monster with a taste for chilled roe cubes. It was killed when Karkat's computer exploded as a result of running Sollux Captor's Mobius Double Reacharound Virus, thereby implementing the curse (if curses are a real thing) that leads to the death of the other trolls' lusus as well. An interesting note is that it died concussively, leaving Karkat's anonymity intact by not bleeding.
Karkat later prototyped his dead lusus into his Kernelsprite.