Karkat Vantas, a main character in the popular internet show "Homestuck" , is currently not dating anyone. However, in the past he did have romantic relationships with other characters in the show.
Karkat's first relationship was with the character Terezi Pyrope, whom he was in a relationship with for the early parts of the show. This relationship ended once Karkat realized he did not have the same romantic feelings for Terezi as she did for him.
Later on, Karkat becomes involved in a complicated relationship with the character Vriska Serket. Though their relationship is turbulent, it develops over the course of the show and eventually becomes quite serious. Though their relationship does not last, Karkat remains emotionally impacted by his time with Vriska.
Finally, Karkat is seen in the show to be friends with (and potentially attracted to) the character Nepeta Leijon, who he interacts with frequently. However, at the end of the show, it is still yet to be determined if these two become involved romantically.
In summary, Karkat Vantas is not currently known to be dating anyone, but has had to relationships in the past. He has a complicated history concerning relationships with the characters Terezi Pyrope and Vriska Serket, and may or may not be interested in Nepeta Lejon.