If Karkat is the troll version of John, then Virgo is the troll version of Rose. They look alike, talk alike, and their mutual need to be smarter than everybody else has lead to a hilarious game of intellectual tug of war between the two of them.
Unlike any of the other trolls, GA has focused all of her attention exclusively on one person: Rose. The one time she spoke to Dave, it was to ask him for more information about her, and she has otherwise ignored the other Sburb kids, only talking to John because he was impersonating Rose at the time.
Rose has likewise been enjoying their interactions, so I’d go so far as to say that they’re the most obvious ship at this point in the story. They really do just seem to be made for each other.