AK unimproved river play

[RunDownHouse]

I don't have experience in these games.

What is he c/c'ing here? AJ? really? It seems like a bet would have to come with the hopes of folding out a split, really, because I just don't see him folding a hand like 77 after previous action.

You're UTG and raised, so he should weight your hand to the better end of your range. Its hard for me to think of too many hands in that range that would flat callt he flop and check behind that turn that hadn't whiffed by the river. So his river check is thinking you've whiffed and wouldn't call one anyways?

EDIT: I'm putting his range as some decent PPs and broadway-type hands. Just about every hand in this range bets the flop. Those that check the turn are the lower PPS and the draws, with the rare A9s or something thrown in, right?