PokerStars No-Limit Hold'em, $2.00 BB (2 handed) - Poker-Stars Converter Tool from FlopTurnRiver.com

SB ($228.80)
Hero (Button) ($495.10)

Preflop: Hero is Button with K, 5
Hero raises to $6.00, SB calls $4.00

Flop: ($12.00) K, J, A (2 players)
SB checks, Hero bets $6.00, SB calls $6.00

Turn: ($24.00) 5 (2 players)
SB checks, Hero bets $12.00, SB calls $12.00

River: ($48.00) 8 (2 players)
SB bets $32.00,

Total pot: $48.00 | Rake: $0.50

He's pretty laggy postflop, but he rarely gets out of line or calls more than once on a total whiff. I also notice he tends to give up right away if he whiffs an ace high board. Best I can figure he's got A8, or, less likely, something bigger than that he's been slowplaying.

Don't see an option here besides call, really. Bet more on turn.

I'd bet more on both streets and call river

I agree with you both on a bigger turn bet, but the way he's played big flops like this I'm pretty confident half pot is enough to either get him to dump a miss or establish that he's got a piece of it. I don't think he'd just float me there. On the other hand, maybe he had J8 and I'm a donk.