Q7s, fivehanded, on the button

I went ahead and raised this my standard 4BB. SBminraised that... I didn't like it but neither did anyone else so I called and we're HU.

Pot 17BB
Flop: J7x rainbow

Meh. SB bets 10BB. Looks like overcards to me. I raise him 10BB more. He calls

Here's where it gets interesting.

Pot: 37BB
Turn J
SB checks

It gets better later but I'd like comments before we continue. SB is somewhat-tight, not real aggressive ... chases now and then ... overall just not a very exciting player.

Oh, and "fold preflop" is a perfectly valid thing to say, but let's just stipulate that for now. I'm in the mood lately to look at cheap flops and practice postflop play. I've got nearly 200BB in my stack, here

I can't see the SB chasing anything here because of the re-raise and the flop that followed.

My guess is AK? QQ? 77? (how many guesses do I get?!!) and he checked to you on the turn hoping you would bet on the J.

he has king jack

you're beat or he's an extremely bad passive player