50 nl 2 pair facing resistance on the turn

[cooker3]

Full Tilt Poker - No Limit Hold'em Cash Game - $0.25/$0.50 Blinds - 6 Players - (LegoPoker HH Converter (http://www.legopoker.com/hh))

SB: $20.50
hero (BB): $51.15
UTG: $18.70
MP: $52.45
CO: $47.20
BTN: $58.50

Reads: <font color="blue">Villain is 35/0/.78 and seems a bit of a calling station</font>

Preflop: hero is dealt 4/images/graemlins/heart.gif A/images/graemlins/spade.gif (6 Players)
2 folds, CO calls $0.50, BTN calls $0.50, SB folds, hero checks

Flop: ($1.75) 4http://legopoker.com/hh/images/diamond.gif A/images/graemlins/heart.gif K/images/graemlins/spade.gif (3 Players)
<font color="red">hero bets $1.40</font>, CO calls $1.40, BTN folds

Turn: ($4.55) 4http://legopoker.com/hh/images/diamond.gif A/images/graemlins/heart.gif K/images/graemlins/spade.gif 6/images/graemlins/spade.gif (2 Players)
<font color="red">hero bets $3.60</font>, <font color="red">CO raises to $15.35</font>

Pot Size: $23.50

Eh, wasn't expecting that. Wtf does he have. There is only 1 combo of set of 4's, he surely can't have aces or kings. Does he really limp with ak?
I was lost here.
Thoughts?

[Genz]

Well, when he has a PFR of 0 over a considerable sample, he can have AA or KK here. There are actually players who will never raise before the flop because they say that only when they know the flop, they can see if their hand is worth anything. And people certainly limp with AK. I fold here, because villain seems to be passive overall and he is rasing you a strong amount. He won't do it with a flush draw. Easy fold, imo.

[iwa]

I'm wondering if he made some kind of stupid 2 pair like a6 or k6. He's not folding either so I'm probably reraising since k6 is more likely and I think he would be more apt to raise a6 on the flop.

Personally, I c/r this flop.

[Peter Harris]

man, that is odd. You have A/images/graemlins/spade.gif so villain isn't even lagging it up slightly with the NFD...

I would expect this to be one of the following - 66 for the turn set, A6/K6 for turned 2 pair, *maybe* 44 for the set, or a flush draw (discounted a lot since its not A/K hi), A4 also (not very likely).

Problem is you may have to call a river bet too if you call here. It's a PSR and you can expect further betting and your hand is good, but a raise on the turn usually beats 2 pair, right?

I say fold, but only because i'm hopelessly lost and can't figure him for much besides a turned set or higher 2 pair. If he has AQ and "waited for the turn" then props to him for his weirdness.