Villain is a middle aged French gentleman. He rarely folds preflop but raises only the very top of his range (I estimate 88+, AK). Postflop, he is sticky and can be unpredictable. Last time I played with him, he ran extremely well and built up a £2000 stack from an initial £200 or £300 buy in, before losing all of it (along with another 2 or 3 buy ins). Effective stacks are £250.

UTG Straddle £4
2 Players call
V (sb) call
H AQo (bb) raise £26
V calls £26

Pot Size: £64

Flop: A J 9 rainbow

V bets £13
H calls £13

I felt this was most likely a defensive bet with Jx, 9x or a weak Ax. I'm aware that he might also bet 2 pair like this to induce a raise.

Pot Size: £90

Turn: 6

V bets £50

I tank because I'm really confused by this line. Villain smiles and says "I know what you have".

I'd be very surprised if V bet small to induce a raise. That's not a play I expect to see from a regular 1/2 player. I think if he were capable of that level play, you'd know it.

I feel like the small bet followed by a much larger one is usually a strong hand.

Against most 1/2 V's, I'd probably fold this. They tend to make calling errors rather than betting errors, and aren't likely double barreling into PFR with a bluff.

I could see the temptation to call one more bet to see if he shuts down on the river.

I wouldn't raise; that's mostly just going to help V play his hand better.

I'd need a good handle on V being aggro before I'd call another bet.

+1

I would call the turn here. He has a few draws that might play this way, QT and T8. Although he probably bets larger as a semi bluff on the flop or goes for a x/r.

If he made a set with JJ or 99 I don't think he would lead out small. He is going to want to build a pot here.

I would put him on a draw, 2 pair, or a weaker A.

I would have raised the flop. Potentially less expensive to find out where you stand than simply allowing V to set the price on turn. I probably also raise to more like $40 preflop and am very happy if everyone folds (crappy position with just a so so holding).

What is our plan for the river is we call 50 OTT? V will most likely shove...are we simply folding unimproved?

Raise flop. Don't allow V to set the bet size like this. If he checked you'd bet, you can't let him change what you do with a 1/5th pot bet. Raise anything you would have cbet if he checked.

Call turn. I think it's really unlikely that he played 2 pair+ by donking 1/5th pot on a board like this where you're very likely to cbet. He'd just c/r. Moreover, it's really hard for villain to have us beaten here. If he had AK, AA, JJ, 99 he'd probably raise pre, that just leaves AJ, A9, J9, A6. Not many combos really.

"I know what you have" probably means he thinks you have KK or QQ. Look at it from his point of view, you look weak as hell. You couldn't muster a raise to a 1/5th pot bet OTF and now are looking worried about a halfpot bet on the turn.

This seems contradictory. Nothing changed on the turn, so if you're saying villain has a strong hand now, you're saying he led 1/5th pot with a strong hand (A6 aside). Presumably this was hoping for a raise.

I think it's crazy to fold here. OP's description of this player included the word "unpredictable". You're saying you don't have enough information to call, but you're putting enormous weight on your ability to read what this small bet - larger bet thing means. If we instead take the position that we just don't know what it means, it's incredibly unlikely, from a combinations point of view, that villain has a better hand than AQ on this board.

Should also be noted that villain, given his own tendencies, will expect a large raise out of the blind to be a premium hand. He expects like TT+ AK probably. I read the $13 bet OTF as a "see where I'm at" bet, villain maybe having a bad ace and expecting to get raised by AK. Hero flat calling is a green light to villain that his ace is good.

I’d call and call all rivers. There’s not much sense in raising at any point and your hand is too strong to fold at any point.

I occasionally see LLSNL V's lead small with a strong hand. I doubt they're hoping for a raise (they rarely get it). I think they're just trying to get some calls to put more money in the pot.

Then on the turn, if someone shows interest by calling the flop, they tend to bet larger from some combination of thinking their opponent may call a larger bet 'cause they likely have something and fear because the turn usually brings something they can be scared of. Sometimes, of course, the turn has also helped their hand in some way and so they bet larger because of that.

In any case, for a variety of reasons, I proceed cautiously when a V leads small OTF and large OTT.

It's heads up on the flop. I dunno it seems super unlikely to me that heads up on an Axx flop a villain who has flopped really well is going to conclude that what he should do is donk 1/5th pot. I mean it's not like he's doing that thing where he makes the nuts and panics, he doesn't have top set here. He's very unlikely to have better than a fragile two pair. I get the bet small, bet larger thing in general but this situation in particular seems all wrong for it. There's no way I'm confident enough with what he's doing that I'm just mucking a strong top pair OTT on a board with no straights or flushes. Note also that turn card is neither a scare card nor likely to have improved villain's hand.

Preflop: raise to $32. You want to be raising to 5x + x per limper when you're OOP on a loose-passive table, and there are 3 limpers. Your open sizing is too small.
Flop: As played, raise to $45 for value. Fold if he 3bets flop. You're going to be ahead at least 90% of the time here when he donks this small on the flop.
Turn: As played, call the turn bet and shut down on rivers if he bets more than $40 and you don't improve.

This

Maybe folding kx/8x

Mostly this.

On the river with 160 left in stacks and 190 in the pot, I mostly snap call bets of up to 80 and consider calling up to a 160 based on live reads.

I agree with most of this but I'm not sure about raising the flop. If this is a defensive/information bet with Ax or worse, a raise gives him information that will be potentially helpful. When we flat the £13, he likely feels confident about his hand and this may induce further bets with hands worse than AQ.

I raise the flop. If he re-raises, you can fold. However, I don't want him to set his price, which is what it seems like he's trying to do.

As played, call the turn and evaluate river.

Unfortunately, those further bets are also likely to be £13.

There's a complicated discussion could be had here about different types of players and their motivations for betting this way, how we best counteract each of them and so on. But to boil it all down, when my opponent bets this way, it's invariably that they don't want to face a big bet, for whatever reason. So I like to invariably disappoint them. I get the argument for hyper-exploitation, that we should flat good hands and raise bluff hands, the problem is that in my experience there are a good number of players who aren't folding bad aces to a raise. And I have a fair bit of experience because I raise the vast majority of the time in these spots.