What would you do?#112 - Interesting second pair call

I don't know whether this was a good check on the turn, but I think this was a pretty well-played hand:

Full Tilt Poker $0.25/$0.50 No Limit Hold'em - 9 players
The Official DeucesCracked.com Hand History Converter

SB: $51.00
Hero (BB): $101.85
UTG: $22.15
UTG+1: $50.75
UTG+2: $20.85
MP1: $30.85
MP2: $60.15
CO: $67.85 - 19/13/0 ats/ 0.0 3bet / inf aggr @ 16 hands
BTN: $47.00 - No info on Button


Pre Flop: ($0.75) Hero is BB with 2c Tc
5 folds, CO calls $0.50, BTN calls $0.50, 1 fold, Hero checks

Flop: ($1.75) Td Ad 9h (3 players)
Hero checks, CO bets $1, BTN calls $1, Hero raises to $3.50, CO calls $2.50, BTN calls $2.50
Semi bluff for me; weak CO bet, flat BTN call is scary, but I really want to press both of them.

Turn: ($12.25) 6c (3 players)
Hero checks, CO checks, BTN checks
Talk about a brick; I was trying to check raise here again, depending on the size of the CO's expected bet, but it didn't work out.  I thought a lead here would be too fishy.

River: ($12.25) 7s (3 players)
Hero checks, CO bets $6.75, BTN folds, Hero calls $6.75
To recap, I check / raised the flop... in CO's eyes "on a draw."  I've now checked the last two streets.  CO has to think he can take me off of my hand...  had he bet pot or over pot, he probably could have.  As is, though, he gives me a great price to call with my bluff catcher.

I can't put him on a single hand that he bets the river with that beats me, where he's not re-raising the flop or leading the turn.

Final Pot: $25.75
Hero shows 2c Tc (a pair of Tens)
CO shows Jd Kd (Ace King high)
Hero wins $24.50
(Rake: $1.25)