「話し合って、どうすると？ カルナスの市民を助けるため、この場を明け渡し、みすみす ヴァネッサがパンドーラに向かうのを許せとか？」
What と is it in the above?
I think it's the と used to quote, but how does it work in the above?
I guess my question is what do they mean by どうすると?
Does this mean "in what way will you tell me to act?".
Or does it mean something else?
「[話]{はな}し[合]{あ}って、どうすると？」
That 「と」 is indeed quotative as you guessed. If so, where is the verb that follows the quotative 「と」? It is just left unmentioned.
In meaning, that question is the equivalent of:
「話し合って、どうすると言いたいの？」
「話し合って、どうすると言っているの？」
「話し合って、どうすると考えているの？」
Note that the unmentioned subject of the unmentioned verb 言う/考える, etc. is "you" the listener this speaker is talking to.
To intentionally form a highly unnatural sentence without any words left unsaid so that Japanese-learners might understand the original sentence, how about this?
「話し合って、どうすると、あなたは言って（or 考えて）いるのですか？」
= "What are you saying/thinking that we should do after talking it over?"
