I don't see villain having AK. Surely he would raise the flop nearly 100% of the time.
K7 unlikely.
K5 unlikely.
I think his most likely hands are 77, KQ and KJ. Maybe KK, but that would be kinda sick.
I don't see how the ace changes anything.
Are you missing the fact that he might have pocket Aces and he's affraid of someone having three Kings until he sees the Ace.
- he doesn't want to push the flop
- he bets $8 to see where his aces are and there is no raise ! he knows at this point you dont have a king ( with random ).
- on the river he has the nuts.. so he has to bet, since the only thing you could have on the turn was pocket kings with no raise.
- You've signaled to be slowplaying something. At best he has to put you on AK or KK here. So indeed he has to bet and not be happy about it.