JTs faces flop min-check/raise

[ajmargarine]

Reads: Villian tries to be tricky and trappy somewhat. He bluffs scare cards quite a bit with air. He's also overbet the nuts a few times and gotten calls. He seem's OK, but is unpredictable. He's pretty passive preflop but can get aggressive postflop. This session I've raised his preflop limp to $13 at least 12 times. About half those times he called me preflop and c/f'd to my continuation bets. This is the first time he's played back at me. (I've also done this quite a bit with other players at the table, as they all have been real passive preflop).

$1/$3 NLHE 5-handed (Yes, this is online, my small site has some weird limits between NL100 and NL1000).

Hero ($350)
Villian ($420)

Preflop: Hero is MP with J [img]/images/graemlins/diamond.gif[/img] T [img]/images/graemlins/diamond.gif[/img]. SB posts a blind of $1.
Villian calls $3, Hero raises to $13, 3 folds, Villian calls $10.

Flop: ($28.50) K [img]/images/graemlins/diamond.gif[/img] T [img]/images/graemlins/spade.gif[/img] 3 [img]/images/graemlins/diamond.gif[/img] <font color="blue">(2 players) </font>
Villian checks, Hero bets $20, Villian raises to $40, Hero??

I had settled in to betting $20 the last few times I raised to $13 and got one caller, whether I had the goods or not, so this is what they've been seeing for the last 20 minutes out of me in this situation, a $20 bet.

What should Hero do, and what's his plan for the rest of the hand?