PokerStars 2/4 Hold'em (9 handed)

Preflop: Hero is CO with , .
UTG calls, UTG+1 calls, 3 folds, Hero calls, Button calls, 1 fold, BB checks.

Flop: (5.50 SB) , , (5 players)
BB checks, UTG checks, UTG+1 checks, Hero bets, Button calls, BB folds, UTG folds, UTG+1 folds.

Turn: (3.75 BB) (2 players)
Hero bets, Button calls.

River: (5.75 BB) (2 players)
Hero checks, Button bets, Hero raises, Button calls.

Final Pot: 9.75 BB

Or is it only a T bets there?

Hmm... A T would bet here, as would a 5 and a small flush, or even a bluff that thinks you're scared of the straight... Two of those you beat, one of them you don't. He's just sitting there like a sponge, so a flush draw is certainly possible.

That said, inspired by Tiburon's treatise on aggression in LHE, I'd probably play it the same way...

I'd call the river bet. If he has the flush you lose that one BB. Unless he is a habitual bluffer this looks like a flush or a T.

oh you checkraised river didn't see that before, in that case we'd play it different, just lead it next time I don't want a weak ace to check behind.