Pre is standard for me. Flatting 4bets OOP is odd. I've not much clue on ranging but I'm not really up for folding and overpair in a 4bet pot. Just jam and be annoyed when he flips JJ? Or Check flop and avoid it in the first place. Sub question. What in gods name is he flatting 4bet OOP with?

PokerStars - $0.10 NL FAST (6 max) - Holdem - 6 players
Hand converted by PokerTracker 4: http://www.pokertracker.com

Hero (BTN): $11.59
SB: $26.94 (VPIP: 27.78, PFR: 22.22, 3Bet Preflop: 14.29, Hands: 18)
BB: $21.39 (VPIP: 41.18, PFR: 29.41, 3Bet Preflop: 0.00, Hands: 17)
UTG: $25.06 (VPIP: 37.50, PFR: 31.25, 3Bet Preflop: 9.09, Hands: 66)
MP: $13.52 (VPIP: 19.16, PFR: 14.95, 3Bet Preflop: 1.25, Hands: 220)
CO: $7.62

SB posts SB $0.05, BB posts BB $0.10

Pre Flop: (pot: $0.15) Hero has Kd Kh
fold, fold, fold, Hero raises to $0.25, fold, BB raises to $0.70, Hero raises to $1.85, BB calls $1.15

Flop : ($3.75, 2 players) 5c Jd 2d
BB checks, Hero bets $1.55, BB raises to $3.10, ?