3/5nl live at a casino in Milwaukee. Villain in the hand is a middle aged guy with whom I have a lot of history. He is constantly trying to make hero calls against me. Over the past few months I have essentially stopped trying to bluff him in big pots, and yet he continues to pay off river bets. He generally plays very loose preflop, and a bit more fit or fold post flop. He was drinking prior to this hand, and thus is playing even looser than normal.

Villain has about $1425 and I cover. Villain is sb.

UTG limps I raise 9Tdd to $30 in mp. Button (fish) calls, sb calls. limper folds.

Flop ($100) Qd 9c 8d.
Villain leads out for $65. I raise to $195. Button folds. Villain thinks for a few seconds and calls.
** I am not sure what to make of his lead, as he does not do it very often.

Turn ($490) 3s
Villain checks, I check behind.

River ($490) 9s
Villain bets $300 quickly. He has $900 behind. I...??

What he's doing in this hand does not really go with your reads on what his leaks are. You claim he likes to call light, but here he has bet twice. There is no reason to think his range is so wide that you can raise for value. So I'd either call or fold--probably call as he might have just a queen or (probably rarely) busted diamonds. But that's all you beat here, and he could also have JT or a boat.

If he has just a Q I'd think he would plan to check/call the river.

To me his line looks more like he has a monster that he bet on the flop to protect vs the FD, then decided to slowplay when you raised. Then he lead on the river for fear of you checking behind.

Would he raise AQ, KQ and over pairs pre? If so I think the only hand that we're beating that might bet the river for value is Q8, IMO.