[FlopYouDead]

Let's put villain on a hand.

He flat calls pf. So if he's semi-reasonable he has a marginal hand that plays better 3way than HU. Ax and pocket pairs do not fit that category. Ax and med-small pairs are horrid oop 3way.

He check/calls flop. He doesn't have any of it. We know in hindsight he isn't slowplaying anything. He must raise a pair here. The call is either a loose peel or a high card, where we've already discounted an ace, which also takes the 3 and 5 out of play.

Turn is a total brick. He check/calls. He has a high card.

River is the ace. He checks. Anything is possible at small stakes. A guy calls with ace high thinking it's good, then checks an ace fearing it's outkicked. Or he calls down with an ace thinking it's good, then wants to c/r river thinking maybe we have a hand. It's possible he thinks the only way to get a bet is to let you bluff.

But the likelihood is it missed him and he has K high. If K high was good on 3rd street it's still good. I think you can bet this. In the heat of the moment I would probably check, but getting paid off by KJ would be awesome. Great metagame.