7 handed Delta poker.

HJ open raises. He plays every hand. I'd estimate he open limps 60% and raises 40%. What he raises and what he limps seems random. I've seen him open 62o UTG because he said he couldn't win with big hands so he raised junk. He donks a ton of flops. I've seen him donk top set and I've seen him donk bottom pair. I haven't seen him donk draws but a lot of his donks he hasn't shown down.

CO 3 bets. He is a TAG who seems to play fit or fold post flop in capped pots. He is aware of how HJ plays.

I cap on the button with ATo. The BB and the rest call.

9d5c4s...HJ donks, CO insta folds, I call and BB calls.

9d5c4s5h...HJ bets....The BB is telegraphing a fold. I feel like it's very possible that the CO and BB may have cards I need if behind. The HJ could have a 5 or bigger. His range is uncapped pre. If I call the turn I feel like I need to call the river. I'm sure HJ has bluffs in his range but from what I've seen he mostly is betting value.

Is this just a standard call it down and hope for the best UIP? It seems like the pot is too huge to fold on the turn but I don't love my hand.

I would fold preflop. Not close.

CO being a TAG, 3! range might not even have ATo but if it does, certainly at bottom of range.

Maybe I’m too nitty, but what flop can you go crazy on short of TTx???

Don't fold.

Now that we've created a big pot by capping pre, don't underestimate the "this is my board texture" behavior from a guy playing too many hands and having a frustrating night. Add in the BB being a thorn in your side and the fact that you likely want to call most rivers if it gets HU, but will also hate a number of them that aren't Aces or tens, and this seems like a spot where if you want to continue you will raise. You know you have nothing, but the BB is likely to respect your turnraise after the cap pre, so getting the isolation is worth the extra bet since it seems like you're feeling sticky anyway.

Looks fine and don’t fold