PokerStars - $0.50 NL FAST (6 max) - Holdem - 6 players
Hand converted by Holdem Manager 3 : http://www.holdemmanager.com

BTN: $69.62 (139.2 bb)
SB: $34.03 (68.1 bb)
BB: $55.12 (110.2 bb)
Hero (UTG): $53.90 (107.8 bb)
MP: $57.02 (114 bb)
CO: $45.94 (91.9 bb)

SB posts $0.25, BB posts $0.50

Pre Flop: (pot: $0.75) Hero has 6h 6s
Hero raises to $1.25, 3 folds, SB calls $1.00, BB calls $0.75

Flop: ($3.75, 3 players) 6c As 8s
SB checks, BB checks, Hero bets $1.78, fold, BB calls $1.78

Turn: ($7.31, 2 players) 7s
BB checks, Hero checks

River: ($7.31, 2 players) Ac
BB bets $4.97, Hero raises to $14.91, BB raises to $27.85

what do we do in this spot? I have 0 hands on villain do not even know if it is a recreational or regular player but seems to be a regular when I look at his betsizing and he donkbet quiet fast when I checkraise him does he ever has worse? or only 88/A8. I did check the turn but then again it was a 3way pot which makes everything a bit stronger will he do this with for example KQs? or is this a easy call without any read?
I would assume he would call the raise with any Ax or flush? but do not know what to do on this river vs the minbackraise.