100nl, go to war with KK?

Pokerroom 100nl full ring

Wtf is going on?

Hero 117
MP 81
villain 97

Image is TAG, villain has been tight passive so.....

preflop
MP raises to 4, Hero raises to 12 in LP with K [img]/images/graemlins/heart.gif[/img]K [img]/images/graemlins/diamond.gif[/img], Villain calls in BB, MP calls.

flop
9 [img]/images/graemlins/club.gif[/img]4 [img]/images/graemlins/heart.gif[/img]8 [img]/images/graemlins/diamond.gif[/img]
pot 36

Villain leads for 20, MP folds