This is first or second hand of HU, rest of table all left. Opponent probably plays higher, joined table and was recklessly aggressive, has calmed down considerably.

BU (Hero) 420 A A Q T
BB - 400

Preflop
Hero raise 3
BB raise 9
Hero raise 27
BB call

Flop (54) J 7 5
BB check
Hero check

Turn (54) J 7 5 A
BB check
Hero bet 38
BB call

River (130) J 7 5 A 6
BB bet 97
Hero call

I have a couple questions.

First, what should we be thinking about for turn bet size in this spot?

Second, any chance we find a fold on this river against a pretty unknown opponent? T98, 864, and even 432 all get there. What about an offsuit T on the river, crying fold then?

Finally, if checked to on the river, how small are we betting?

Thanks!

Honestly I think this is a fold a lot as it's an odd line to bluff spades especially when you 4b pre and your line looks like AA.

Fold is reasonable. You want to be blocking their value range when you hero call.

Turn sizing is fine. 66-80% is probably my standard.

400bb effective is more than just deep, would seriously consider not 4betting.

Note that both 98 and 43 are an open ender on the turn, and you probably don't have spades. Sucks though because I'd feel like my hand was face up. Also means we are folding everything except like AA98 or _maybe_ JT98ds without spades.

We certainly flat a lot of AA, but I think IP we can still do it, and AAQT is an ok combo. I think it would be mixed with 2 clubs. 3 clubs, well, people play poorly enough leaning towards 4betting more is probably okay.

I mean, we can call with better blockers too, it doesn't have to be better than a set.

I think we can call river for that price / 30%, but fold totally reasonable on this runout / no blockers.