villian was 40/5 over about 40 hands
Bet more on the flop in case he's on a flush draw?
Turn bet was weak... I know, I know
Did he hit the flush and decided to slowplay? Was the river bet a weak-bet trap? But he bet 0.25 into a 0.85 pot on the flop.
I almost used all my time thinking about this one before I ...

PokerStars No-Limit Hold'em, $0.10 BB (5 handed) - Poker-Stars Converter Tool from FlopTurnRiver.com

SB ($7.60)
BB ($9.75)
Hero (UTG) ($16.15)
MP ($10.20)
Button ($4.95)

Preflop: Hero is UTG with J, J
Hero raises to $0.40, 3 folds, BB calls $0.30

Flop: ($0.85) 7, J, 4 (2 players)
BB bets $0.25, Hero raises to $0.80, BB calls $0.55

Turn: ($2.45) 5 (2 players)
BB checks, Hero bets $1.30, BB calls $1.30

River: ($5.05) 2 (2 players)
BB bets $1, Hero ???