Flush on a two paired board

[Verde]

$15-$30 HU
We'd played 150 hands or so and Villain seemed passive especially on the turn.

Villain posts blind ($7.50), Hero posts blind ($15).

PRE-FLOP
Villain bets $22.50, Hero bets $30, Villain calls $15.

FLOP [board cards 7C,3D,7D ]
Hero bets $15, Villain calls $15.

TURN [board cards 7C,3D,7D,3H ]
Hero bets $30, Villain bets $60, Hero calls $30.

RIVER [board cards 7C,3D,7D,3H,AD ]

Hero?
Bet/folds Since he's passive?
And check/call if he's aggressive?
And if he's unknown?

[Hi5]

Check-call, since you called on the turn.