My dumb ass thinking about what sort of complicated little thing (triangle?) Match, Thad, and Superboy Prime could have. (It's also just an excuse to smoosh my favs together.)
Thad's curious about Superboy Prime and his universe, reality, and fourth wall breaking abilities from a scientific perspective. There also might be some lingering annoyance towards him for associating with/teaming up with some random guy who took his identity as Inertia.
Match is pissed at Prime for killing him and dissecting him to make his other clones, so he has a natural dislike of Prime. He also dislikes how interested Thad is in him even if it's just because of Prime's association with the multiverse. Match does have feelings for Thad in this scenario. They might casually be a thing.
Superboy Prime's willing to indulge in Thad's curiosity about how his powers work because he doesn't get to talk about his universe breaking abilities with others often of in depth. Things get nerdy between them. I think part of him would also be a bit of a shit, notice Match's feelings for Thad, and play into Match's insecurity/jealousy/dislike of him being so close with Thad just because it's funny to stir up a bit of trouble (and he gets to see how things play out).