In general, I treat the "donk bet" as a check unless I have some specific history with the villain that tells me otherwise. So, if I was going to bet, I raise. If I was going to check, I call. God, I fucking hate the donk bet. As far as what to do in this hand specifically, I would say that you have probably found yourself in sitiuations like this far more than I have. I like raising more than calling. I don't like having the button behind me who can cripple me. MP2's bet seems non-comittal with FE. Why did you want to get youself in this spot again?
im kind of a call box to be honest especially this deep actions, and why i think the way i do....
fold...out of the question on this flop getting 6:1 after i make a marginal preflop call, and ill agree its marginal, i just think if youre comfortable post flop its fine in position where you can somewhat manipulate the size of the pot.
raise...possible to get blown off my hand if hes tarp raising KK or big diamond draws, some people that mix in donk bets like to donk lead KK here and then flat 2 streets of an overagressive players raises (thats me). any info i thought i had now im questioning. hes either really bad and donk leading marginal hands here like 99-QQ, or playing KK or any set funky. i cant imagine someone playing AK this way, not that its out of question. also who knows what he does with say...AQdd, i think he has some hands he folds to me if i raise, or some hands that im way behind and i dont get any additional information if i raise and he flats.
call...getting correct odds, someone left to act behind me so i dont invest much if BTN wants to cold 4 bet a flush draw, set, or combo, his flatting range is even scarier if i raise, its just not something i want to think about or get involved in. throwing more chips in at this point when im getting basically a free shot at it, is kind of wasting chips, i think. i still have two more streets if i want to move this person off their hand and i get additional CHEAP information on the BTN's hand by calling.
also if i raise its gonna be really hard if i get flatted by mp2, im pretty much never checking behind on any turn so im making the pot bigger, i have no idea where i am, and im guaranteed to proceed as if i have FE on the turn and river which leads me to barreling off more of my chips.
plus, there are some great turn cards that i can bluff at and i get additional info from MP2 on the turn
I would fold, or call with anything if your calling in that spot, also I like raising more then calling and folding more then raising, and I hate raising.