Fire the third shell?

This guy just sits down, post the blind, and stacks KK with a set. 10 hands into it he seems like the weak/passive type. 53/5/2 Likes to see flops, especially suited, and likes the pots small. Has gone to showdown a few times showing suited cards that turned into midpair or a gutshot. Do I fire at it agian or just give up?

Full Tilt No-Limit Hold'em, $0.25 BB (8 handed) - Full-Tilt Converter Tool from FlopTurnRiver.com

saw flop

Hero (MP1) ($33.48)
MP2 ($23.95)
CO ($24.55)
Button ($23.26)
SB ($25)
BB ($25.62)
UTG ($26.38)
UTG+1 ($47.66)

Preflop: Hero is MP1 with Ahttp://www.flopturnriver.com/phpBB2/...es/diamond.gif, Qhttp://www.flopturnriver.com/phpBB2/...iles/heart.gif
2 folds, UTG+1 calls $0.25, Hero bets $1, 4 folds, UTG+1 calls $0.75

Flop: ($2.35) Khttp://www.flopturnriver.com/phpBB2/...miles/club.gif, 5http://www.flopturnriver.com/phpBB2/...es/diamond.gif, 2http://www.flopturnriver.com/phpBB2/...miles/club.gif (2 players)
UTG+1 bets $0.25, Hero raises to $2, UTG+1 calls $1.75

Turn: ($6.35) 3http://www.flopturnriver.com/phpBB2/...es/diamond.gif (2 players)
UTG+1 checks, Hero bets $3.50, UTG+1 calls $3.50

River: ($13.35) 3http://www.flopturnriver.com/phpBB2/...iles/spade.gif (2 players)
UTG+1 bets $1

Total pot: $13.35

what?

described villain is a station and the river did not improve your range or scare his AAAAAAAAAAAAAAAAAATTTTT ALLLLLLLLLLLLL!

EDIT: just realized that villain donked into you. you beat all of his busted draws, so you might as well just call with those ballin 14:1 pot odds