Villain is new fish who plays really fast (and impulsive?). He has BLUFFER in his name.

check/raise best line here?
I'm scared of being behind Tx. so if I bet/call he could jam TP. he would have to jam all draws to make bet/call good. I think it's very likely he bets draws to try to make me fold AK AQ type hands.
Vs "BLUFFER" I would check overpairs here quite often. I dunno why he would bet pot with just weak Tx so I assume it's more polarized.
I think the only downside to checking is that we give Jx Qx Kx Ax a free card (that's 16 potential scare cards). but I think vs fish who plays fast check/raise is best line.

I'm also interested in other ways to playh it. I think with 99 we want to end the hand as fast as possible, so we could do 2 streets as well for thin value. Is this good plan?

- €4 NL (6 max) - Holdem - 2 players
Hand converted by PokerTracker 4

SB: €373.20 (VPIP: 50.00, PFR: 11.84, 3Bet Preflop: 12.90, Hands: 85)
Hero (BB): €585.92

SB posts SB €2.00, Hero posts BB €4.00

Pre Flop: (pot: €6.00) Hero has 9 9

SB raises to €12.00, Hero raises to €40.00, SB calls €28.00

Flop: (€80.00, 2 players) 7 5 T
Hero checks, SB bets €80.00, Hero raises to €545.92, SB calls €253.20

I'd just lead out for ~60 and go from there. Your hand has value and you're turning it into a bluff. I'd much rather make this play with big diamonds or a combo draw. I think your line is pretty bad. Almost every hand that beats you will call. Seems super spewy tbh.

I'm not quite sure of why you check this flop?

I would lead out $60. How lose is this player to decent size re-raises pre-flop. That frequency is super key in hand range determination and post-flop play.

As is I lead out $60 on flop. Not sure why you would check on this flop? It's not like it flopped [773] rainbow.

X/r is by far the worst option. Bet/call and reevaluate ott and x/c both have merits.
Depends on his strat, readless I would lean towards betting otf.

I like check/call on this flop. SPR seems to big to get it in here. Check-raising all-in will allow him to play perfectly against you imo. If too many high cards come on turn or river you may have to fold, but remember, you are also 3-betting with AK, AQ, etc which can check/call this flop as well and can hit.

You could also take a bet flop, check turn, bet river line. You can also take a bet flop, check turn, check/call river line. I like check flop, bet turn, and either bet/fold or check/call river line the best. With this last one you can comfortably call 2 streets if he bets out on the flop. If he bets 3 you may have to let it go though.