At the time MP1 is 14/11, cbet 68% AGG inf. Haven't seen him get out of line at all and no other notes. Sample only 40 hands.
Butt is 45/25 aggro fish. 3bet 6%. I have seen him bet OOP a couple of times and raise flops a couple of times only to fold on the turn to any bet and I've seen him double barrel when IP. Sample only 22 hands.

PokerStars No-Limit Hold'em, $0.10 BB (8 handed) - PokerStars Converter Tool from FlopTurnRiver.com

Hero (SB) ($9.90)
BB ($12.37)
UTG ($7.94)
UTG+1 ($12.38)
MP1 ($10)
MP2 ($10)
CO ($3.25)
Button ($18.96)

Preflop: Hero is SB with 9, 9
2 folds, MP1 bets $0.30, 2 folds, Button calls $0.30, Hero calls $0.25, 1 fold

I put MP1 on TT+, AQ+, AJs+, KQs+
I put Butt on almost any two cards. My best guess is probably Ax, any broadway, 22-99 and SC's 65+ and possibly SG's 97+. I discount TT+ as I think he would have raised

I figure it's a good place to set mine. Don't see any value in 3betting OOP agains at least one player who seems fairly solid and I want to keep the fish in if I hit my set.

Flop: ($1) 2, A, 9 (3 players)
Hero checks, MP1 bets $0.60, Button calls $0.60, Hero calls $0.60

Get my set, fairly dry board so I check figuring there is a good chance one or the other will bet.

When MP1 bets I put him on TT-KK figuring he seems good enough he might rep the A along with AQ+, AJs+. AA is also possible of course but very rare.
Butt calls and I put him on AweakX, and some combos of 9x. I can't figure any other hand that he would only call preflop with and not raise this flop.

I decide to just call hoping to disguise my hand a bit and figuring there is a decent chance butt will fire again at the very least if not MP1 as well.

In hindsight a raise here probably would have been better. I figure MP1 would probably only have two moves, being to fold out TT-KK having seen my hand for what it was or assuming I had an A or he would have jammed with AA and such is life.
Butt almost certainly would have called a raise with Ax.

Turn: ($2.80) 7 (3 players)
Hero checks, MP1 checks, Button checks

No real danger from 7c so going with my disguise idea I check figuring at the very least butt will fire off. Bit disappointed but what can you do.

River: ($2.80) 4 (3 players)
Hero bets $1.30, 1 fold, Button calls $1.30

Total pot: $5.40 | Rake: $0.26

In the past in these circumstances I've tried shipping it all in, overbetting, psb and all of them seem to just get folds. So this time I went for about 1/2psb and got the call which was nice but still think I lost a fair bit of value on this hand.