You’re right to be confused/concerned. Villain’s action before the river is highly suggestive of a marginal/bluff-catching sort of hand, but hands like that should prefer to check the river. The fact that he is suddenly taking an aggressive action suggests a more polarized range, and I don’t see him getting to the river with a lot of bluffs, which means he probably has a hand he thinks is strong.

The thing is, your hand is pretty darn strong, strong enough to beat some hands V might think are monsters. So folding is out of the question, and I’d seriously consider a small value raise. I think many people would have raised before now with a set. Although you block K8 and KT, those still seem like V’s most likely holdings to me.

Definitely fold river if Villain 3-bets, though.

FWIW, I’d bet a bit larger on turn, there are a lot of pair + gutter hands V could have that will call bigger bets, not to mention dominated Queens.