Facts about Homestuck Trolls!

Karkat

Karkat Vantas, also known by his Trollian handle carcinoGeneticist, is one of the trolls and is one of the main characters in Homestuck. His associated zodiac sign is Cancer (♋) and he has horns that are rounded instead of pointed (constantly referred to as "nubby horns" or "candy corn.") He types in gray with all caps and near-perfect syntax. His emotes display these nubby horns as the capital letter B, for example, a frowning face is depicted as ):B.
Karkat comes from "Karkata," the Sanskrit astrological equivalent of Cancer, minus one letter. Additionally, his name may be drawn from "Karkinos," a giant crab who fought Hercules of myth, also the origin of the Cancer astrological sign. Vantas, on the other hand, is a prostate cancer treatment drug.

His Trollian handle is a play on the medical term "carcinogenesis" which is the development of cancer in the body (or carcinogens, cancer-causing substances), and "carcinology," the study of crustaceans. The first part of his handle might also be related to "Karkinos", like his first name.

His online handle could imply either a geneticist studying cancer, or someone who creates cancer genetically. This is proven to be the case later on, as he had genetically bred cancer into Bilious Slick by underestimating the importance of the completion of its genetic sequence, thus ultimately dooming the kids' universe. Later Karkat tries to think of a title more befitting of him considering the apparently doomed life he created via Ectobiology. Ironically, he can't think of the obvious choice present in his trollian handle.

His weapon of choice is a sickle. This is most likely to contrast or even complement John's hammerkind, as the hammer and sickle are the symbols of communism and the Soviet Union (this was later directly referenced by Dave), or it may resemble a crab's claw. It may also be a reference to sickle cell disease, or anemia, a sickness of the blood caused by a genetic mutation.

Karkat is a very crabby troll, which is a pun on his sign. In fact, most people under the Cancer sign are said to be moody and crabby like he is.

Karkat was the leader of the Red Team, and leader of the joined teams.