Villain in BB is loose-passive preflop but explodes into aggression on and after the flop. On an earlier hand, on a monochrome board where I had flopped TPTK and nut flush draw, they four-bet the flop and bet the blank turn and river. (I figured my pair was no good, and folded.)

SB plays way too many hands, and plays them transparently after the flop.

Winning Poker Network (Yatahay) - $0.50/$1 (6 max) - Holdem - 6 players
Hand converted by PokerTracker 4

Hero (BTN): 108.95 BB
SB: 52.48 BB (VPIP: 47.06, PFR: 27.45, 3Bet Preflop: 9.52, Hands: 53)
BB: 42.83 BB (VPIP: 47.37, PFR: 3.51, 3Bet Preflop: 0.00, Hands: 57)

SB posts SB 0.25 BB, BB posts BB 0.5 BB

Pre Flop: (pot: 0.75 BB) Hero has J 9

fold, fold, fold, Hero raises to 1 BB, SB calls 0.75 BB, BB calls 0.5 BB

Flop: (3 BB, 3 players) 6 5 A
SB checks, BB bets 0.5 BB, Hero ...?

I flopped a flush draw, and had the action been checked to me I would have definitely bet/called.

If I raise, I would be balancing my raises from hands like AX and big pairs. But raising charges the SB's possible draws more. Since I am drawing myself, I might want to encourage the SB to trail in, to pad the pot should I hit. Moreover, this villain reraises aggressively.

Raise or call? Somehow I don't think folding is a viable option.

I'd raise. It also sounds like folding tptk may have been an error earlier.

i like calling. preserves our ability to raise when the spade comes in and like you said, allows sb to call and pad the pot.

if he's aggressive, then let him drive the action. i would play more straight forward vs his type.

however, if i thought a large portion of his range was a lot of non ace hands, i would wait and raise the turn.

This hand should be pretty clear 3-ways. Just build yourself a flow chart and it should be obvious:

1. Is my hand strong enough to showdown unimproved?
-->A: No
--> 2. Is my opponent bluffable?
---->A: No
---->3. Call (profit).