Help roleplaying Talis the White

[Manahtar]

Hey guys, I'm continuing with HotDQ tomorrow and the players are about to meet Talis, do you have any advice on how to roleplay her?
I'm a bit lost on how a deal can be reached with her if she stays alive, because that would mean that the Cult's objective is going to continue it's course, how can that benefit the players, what can i use to have an interesting "villain-heroes talk".
Thanks in advance

[Zacchaeus]

Talis is there to give the PCs information which will help them deal with later events. If they don't negotiate with her or accept her surrender then they won't get that information. Not really sure there's a whole lot more to it than that.