Oh what luck that I would find this thread within 24 hours!
For this dream I don't remember all the details, but I do recall that I was staying at some place along with maybe six Homestuck characters. Someone different entered the building and took over one of the rooms, and held Vriska hostage (as if someone could kidnap the god-tier Thief of Light, but whatever.) There was nothing in the building that I could use to free her (and the other people there were either unwilling or unable to provide enough help) so I left.
While I was out at some other place, looking for clues or help or whatever that could free Vriska, I came across some sort of crossword puzzle or miniature Scrabble board that she had filled out or at least signed, giving away that she had previously been where I was. I also tried to get some help from some of the other people in the room, but they only spoke Russian and I hadn't remembered enough from high school for anything useful. An interpreter arrived to the scene, but I think I woke up soon after.
I now realize that someone with teleporting powers (other than Jack Noir) would've really come in handy there. Although I cannot confirm or deny that it was Jack Noir himself that kept Vriska stuck in that room in the first place.