Might have the wrong thought process here but guy 3bets a ton like 8% or so. I think flatting is good here, keeping in his worse aces.

When he checks the flop I think:

1) Hes checking to check fold, as check raising this flop doesnt make much sense.

2) Hes pot controlling with tens, jacks..., QK?

I decided on the first and thought checking behind was good and go for a delayed bet. Once he starts firing I see no value in raising, is call down standard?

PokerStars Zoom No-Limit Hold'em, $0.25 BB (6 handed) - PokerStars Converter Tool from FlopTurnRiver.com

Hero (Button) ($26.61)
SB ($26.12)
BB ($9.03)
UTG ($25.02)
MP ($20.56)
CO ($26.03)

Preflop: Hero is Button with A, Q
3 folds, Hero bets $0.75, SB raises to $2.50, 1 fold, Hero calls $1.75

Flop: ($5.25) 9, 6, Q (2 players)
SB checks, Hero checks

Turn: ($5.25) 3 (2 players)
SB bets $3.75, Hero calls $3.75

River: ($12.75) 7 (2 players)
SB bets $6, Hero calls $6

Total pot: $24.75 | Rake: $1.11