Quote Originally Posted by BigPapi
I'm thinking he wants a cheap next card, which means a draw/semibluff, some ace (afraid to valuebet big yet because the draw might hit and he's worried he'll get outdrawn and lose more money).
This ^^

As played, do you really think he small bets 99 on flop and turn?
I think most of the time he's putting you on a weak/average hand and wants you to fold river. I also call river.