I would fold here and not think too much about it. A river bluff here at this level is extremely rare.

What line should I be taking up until the river if not the line I took? turn my hand in to a bluff pre? Donk the flop? C/r the flop? I'm interested to hear some thoughts on alternative lines.

I don't think the river is as clear a bet as some are saying. Thinking that villain has 77+ in his range is pretty optimistic, if anything he's got them some % as this guy can spew, but not anywhere close to 100% of the time.

The fishy reg calling the flop changes things a lot. What is he overcalling the flop with? He has a 6 a lot of the time. When both of you call the flop villain is going to be worried about this and check back the turn a lot, even with QQ+, Your range is also pretty face up as 99-QQ, so villain might be worried that by betting ott he's just freerolling himself, you can't call with most of these, and the fish is probably folding unless he has a 6. Even without the fish in the pot he might check the turn because you fold most of these to a double barrel, and he might think a b/c/b line gets you to call them more often. Therefore villain is checking almost all his range ott. People are putting too much weight on villain's turn check.

Now otr, 6 is obviously a good card for villain because lol who ever has quads? On top of that when you bet out and fish folds it's now 100% confirmed no one has quads and villain is now freerolling with his KK+, maybe even QQ plus if you don't 4bet kk 200bbs deep, so he shoves all these hands, even if he does shove ak sometimes, it's probably not enough to make the river a bet call.

You don't go too much into how big a fish the fish reg is, but imo, if you are betting otr it's to get the fish to call you with worse, not the preflop 3 better. Betting this river in the hopes that villain has a worse hand and calls with it is way too optimistic.

The fish actually had AThh, so that should tell you how big of a fish he is.

Table talk makes me think he had it. He's setting himself up to look stupid if he's bluffing and you call. Nobody wants to look stupid. In fact he's trying to make you look stupid by letting the table know he's weak as you think about folding. Ime goading = they have it

Very interesting discussion, I've enjoyed reading though it.

Getting to a river with a full house that beats the board's against two, what we believe to be, "spewey" players seems like an automatic value bet especially when the turn went check, check, check. From the description, it sounds like either player will call with anything to win half. This being said, usually my play is perceived as at least a little bit "whacky" at the table and I depend on tight spots like this to get value from my image. I also have way more limit experience than no limit.....