The maniac has been at the table about an hour. No other history.

He has raised/3! pre every hand but one or two. C-bet 100%. C-3! often. Bet/raise turn often. I've seen him do this both with a decent hand and with total air (like 73o-high air), but he doesn't do it every time and I haven't picked out any pattern to it.

Hero is UTG+1 with AT

UTG folds, Hero raises, folds to maniac in MP2 who 3!, folds to Hero who caps, maniac calls

Flop (9 SB): JT9

Hero bets, maniac raises, Hero 3!, maniac caps

Turn (8.5 BB): 9

Hero bets, maniac raises, Hero calls

River (12.5 BB): 4

Hero checks, maniac bets, Hero calls

If this thread doesn't get closed for want of barnyard animal sounds, I'd appreciate your thoughts.

I would not have capped OOP, but called his 3! and planned to check-raise good flops and call down most of the rest. As played I would have called down from his flop raise as he seems liikely to bet the turn and river with his entire range.

I like it, but I also like the idea of flatting the 3 bet preflop so we can check call our way to victory when we miss. I think implied bluff catching odds(ibco) more than make up the missed preflop value.

Some maniacs have an "oops! he's got it, I fold" mode and you should have some read on the types of situations and board where he gives up.
You do want to get in there and mix it up with an otherwise marginal hand that is going to be best at showdown a large % of the time. On one hand, your 4-bet might cause him to slow down since not many sane people in ordinary situations cap anything other than big pairs and AK. Otoh, you'll surely continue to get action from him in future hands.
Regarding postflop play, he doesn't seem like the type to take a free card, so you can probably check-call your way to showdown after the flop cap.

I think the cap preflop is fine. Maniacs like this either a) don't know your range is now stronger or b) care even if they know. Honestly, we should probably be capping our whole PFR range in this spot anyways.

As played, I probably Bet/C the flop & C/R good turns. As Man of means has said, villain isn't going to take many free cards and our equity can change a lot depending on the turn.

This is what I was thinking pf. His range is literally ATC which we have crushed with anything I would raise from UTG+1 in this particular game (ballpark let's say 77+,A9s+,KQs,ATo+,KQo, we're at 68%).

I like the point about us being able to k/c when we miss. But can't we do that even if we cap? We have an overwhelming edge at this point. And this guy is going to barrel a lot of the time anyway. Idk, I'm just not really sure the pf cap would affect this guy much, if at all. But it might.

Does being oop matter enough to pass up a near-guaranteed profitable cap? I know capping oop can be a sticky proposition, but does that apply when his range is this well-defined?

He checked a few turns, but bet/raised most.

Can someone explain a little more of the theory behind why we want to k/c turn and river? At most we get 2 BB that way, and those couple times he checks behind, we give him a free chance to draw. K/r or b/c turn and k/c river can yield 3 BB. I bet turn because I thought I was probably still ahead and didn't want to risk him checking behind.

It takes a really really maniacal player to float or raise the flop and fire the turn and river drawing dead with something like 54, but he'll do that often if we flat preflop. That said, I think op's line is good without a better read, straight value with a made hand, no free cards, etc.

Don't cap flop once he 3!'s. Even the craziest maniacs will slow down facing hyper aggression. Unless this guy has some crazy spew in his range here, like 76o

The benefits of just Ch/Calling is we keep all his bluffs in his range (which is presumably a lot of his range.) If we bet the turn he may just call the turn & fold river with his bluffs or he may just fold the turn right there. So when bet we get a little extra value from part of his value range, but we lose much more against all his bluff's he'd be willing to barrel off.

What if he checks behind ott? Would you still check/call river hoping he fires?

Depends on the river, a scary river I would Ch/Call. A brick I would probably just bet. I think when players like this check behind on the turn, they generally have "a lil something". I feel like if they just had air and wanted to bluff they would have bet the turn.

I fold preflop but whatever. Once you raise preflop and the maniac 3bets, it sounds like you have a very profitable cap, so that's what you must do. However, once that flop comes you should just check call down ui. In fact, on ANY flop if you don't hit an ace or a ten (or a straight obv), you should be planning on check calling down ui. Betting the flop in this hand is a clear mistake imo. That's not how you play a marginal showdown hand vs a maniac. Overall I hate the way you played this hand.

Makes sense to me.

It's right on the edge for me. I fold A9o here.

Seems to be the consensus. Good to know for those times I don't hit the flop.

I flopped a T. I don't understand how 2nd pair, top kicker is marginal against this player?