Verey interesting live hand

[Aaron W.]

Bellagio 15/30 from tonight.

I'm actually going to turn the action around and give it from villain's perspective, because I think it's a far more interesting decision from his side.

Some guy open-raises from MP and Aaron 3-bets it. I played with Aaron about a month ago, and I remember him being pretty solid and pretty aggressive. Tonight he's been up and down, but hasn't really shown anything too out of line. He did 3-bet the same guy earlier with TT and outflopped the poor guy's KK. Speaking of KK, I 4-bet him with KK and it gets folded back around to him and he calls.

The flop is QJT with a flush draw and he check-calls (I have the backdoor flush draw). The turn is an offsuit 4 and he checks again...

What are my turn and river plans? Do I raise a rivered straight if a 9 falls and he bets? Am I checking behind here to get a cheap showdown? What if I hit my king? What if an ace falls?