Looks like I need to reread all the stuff about Vriska and Terezi now. Maybe Mindfang was a follower, and she had at least heard of The Sufferer. Plus, Terezi and Vriska were friendlyish, and may have shared the religion, if Terezi was willing to admit her beliefs to a highblood who would almost surely exploit it. I can't remember Vriska's reactions to Karkat though. But this troll would probably be Player-Mindfang if the new universe is sorta-contemporary to the trolls Alpha universe. And I suppose that works if they proceed to create the troll universe at the end of their session. That might work out though, because they would have had Karkat as the Signless, and there wouldn't be a prohibition against his worship, which would probably involve something about romance and how he gets to be the leader.
But if that's the case, then I can't figure out UU unless the current troll universe has 13 players(possible, isn't Ophiocus or whatever snake-related?). That alone makes me like the metastuck idea, even if I haven't read it. I suppose there's a chance that she was created in this universe but not the other one, since things don't need to follow the exact pattern. Maybe something happens and she doesn't get pulled through in their Scratch.