65s hits bottom 2 pair

Home game... $20NL buyin, .25/50 blinds 9-handed
Late at night..around 4am

Hero ($55)
Villain covers

Notes on Villain:

Villain is normally very aggressive, but also knows I'm fairly tight. He's been in line most of the night though, because we're at a large table.

I -have- seen him limp in with big pocket pairs in the past, but it's not overly common.

That said:

Hero is dealt 5[img]/images/graemlins/spade.gif[/img]6[img]/images/graemlins/spade.gif[/img] on the button
3 limpers
Hero limps in

Flop (2.50ish): K[img]/images/graemlins/heart.gif[/img]5[img]/images/graemlins/club.gif[/img]6[img]/images/graemlins/heart.gif[/img]
All checks to me
Hero leads for 2.50
fold,fold,fold
Villain raises to 5.00
Hero calls

Turn: (7.50) 8[img]/images/graemlins/diamond.gif[/img]
Villain bets $6
Hero calls

River: ($19.50) J[img]/images/graemlins/club.gif[/img]
Villain bets $15
Hero calls.

Thoughts?

Preflop: standard
Flop: Should I re-raise/push here?
Turn: Raise the turn?
River: This is a very unusual sized bet for Villain. Normally, I won't see much bigger than a $10 bet from him. $15 is a -large- bet in our home game. Normally people underbet the turn/river because they have no concept of pot size.

He knows I've shown strength - but what can he possibly have? Way overplayed AK? Seems an unlikely bet for such a big hand. AJ? KK? But he limped preflop? (he's done this in the past, just probably 1/10 times)

I rule out a set, because he didn't raise preflop, and i'm holding both a 4 and a 5. The 8 didn't really help any straight, unless he's got something ridiculous like 97, but he already re-raised the flop.

What the hell can I put him on? See results.