Read is villain is tight neutral. I haven't seen him become overly aggressive except versus a short stack.

What hand does he have?

PokerStars No-Limit Hold'em, $1.00 BB (6 handed)

saw flop|saw showdown

Hero ($141.30)
UTG ($103.05)
MP ($57.75)
CO ($54)
Button ($96.05)
SB ($69.25)

Preflop: Hero is BB with , .
1 fold, MP calls $1, CO calls $1, 1 fold, SB completes, Hero checks.

Flop: ($4) , , (4 players)
SB bets $2, Hero raises to $7, MP folds, CO folds, SB raises to $18, Hero ????

66

I get away from top-and-bottom when I face heavy action like this nowadays. The only hand you're ahead of is AK which according to your description he wouldn't go nuts with, and would probably raise preflop. He can only have AQ and 66. I would fold if I were you.

Well, since you out him a tight neutral kind of player. I would say he is eitherAQ, A6 (same as you) or 66. However, if this is one of my wild'n' loose $25NL games I would say that Q6 suited would be a deffinate possible holding out of the SB. Some of these guys will play anything suited!

My final choice is AQ or 66. Either way i fold!