CO is fairly tight, regular aggression. I don't think he'd be raising preflop with either a 6 or 8 in his hand (or pairs of those).
2 questions:
Do I go submissive on the flop after being reraised preflop?
What about the turn?
Could/should you fold the river? Pot is pretty big.

Party Poker 1.00/2.00 Hold'em <font color="#0000FF">(9 handed)</font> link

Preflop: Hero is UTG with 9[img]/images/graemlins/spade.gif[/img], 9[img]/images/graemlins/diamond.gif[/img].
<font color="#CC3333">Hero raises</font>, UTG+1 calls, MP1 calls, <font color="#666666">2 folds</font>, <font color="#CC3333">CO 3-bets</font>, <font color="#666666">1 folds</font>, SB calls, BB calls, Hero calls, UTG+1 calls, MP1 calls.

Flop: (18.00 SB) 8[img]/images/graemlins/club.gif[/img], 6[img]/images/graemlins/spade.gif[/img], 6[img]/images/graemlins/club.gif[/img] <font color="#0000FF">(6 players)</font>
SB checks, BB checks, <font color="#CC3333">Hero bets</font>, UTG+1 calls, MP1 folds, <font color="#CC3333">CO raises</font>, SB folds, BB calls, Hero calls, UTG+1 calls.

Turn: (13.00 BB) 5[img]/images/graemlins/heart.gif[/img] <font color="#0000FF">(4 players)</font>
BB checks, <font color="#CC3333">Hero bets</font>, UTG+1 calls, <font color="#CC3333">CO raises</font>, BB calls, Hero calls, UTG+1 calls.

River: (21.00 BB) 3[img]/images/graemlins/diamond.gif[/img] <font color="#0000FF">(4 players)</font>
BB checks, Hero checks, UTG+1 checks, <font color="#CC3333">CO bets</font>, BB folds, Hero calls, UTG+1 folds.

Final Pot: 23.00 BB.