In order for Minthara not to try to kill us, I would suggest destroying the Druid Grove alone, using only the forces of our party.
After that, she will at least be afraid to betray us and will warn about the decision of the absolute in advance, immediately moving on to the conversation about the fact that she does not want this in the morning after the party (without trying to kill), and will offer help on the way to the Moonrise Tower.
Why should she be affraid?
She have whole goblin army at her disposal, she believes that she have goddess on her side, and she is also quite self confident ... also, if she dont participate on fight, how should she guess your power based on that?
Nah ... this whole scenario dont seem fiting her personality ...
Yes, you should be able to be honest with her ... but in that case you should be striked down as abomination ... after all, Minthara sended her agents to kill everyone who survived that Nautiloid crash ... so why should she be friendly on you, since you "honestly" confess that you are one of her targets? O_o
I like the idea of killing whole groove for her all by yourself (or your party w/e) ... but concidering her personality (and all other mentioned abowe) ... she should more like say something like "then i dont need you anymore" and attack you anyway.
You seem to forgeting that this massacre is the only thing that takes you two close enough so she is even able to think about joining your little journey.
Hmm, but what is the reason for PC to even work for the absolute when it is pretty clear they want make us their puppet and maybe even turn us in mindflayer during invasion day. Minthara is a total stranger. Unless it is a blind love at first sight, PC would rather try avoid working for her or absolute at all cost.
That is ofcourse up to PC to decide ...
Im sorry, i just cant help it ... i find this question incredibly funny ... you are basicly asking us why your character (aka you) should do something ... as if we should know better than you.
Right now i can think about at least 5 reasons for joining the absolute for one
of my characters ... none of them is relevant for another one
By the way, Minthara most likely does not know about the tadpole in her head, and an honest conversation can make her think about the fact that she is also being deceived and manipulated in the second act. After that we will be the only ones who can somehow help protect her from both the Absolute and the clerics of Lolth .. in general, there are many things that Larian can think about
On one hand we have whole cult, powers given her by goddess that she allready uses (so she know that there is some powerful entity), and strong believe in her goddess, maybe almost a little fanatic ...
On the other hand we have complete strainger, that comes here and declare that our goddess and everything around it is one huge scam ... also telling us that we have discuisting tadpole in our brain ... and admiting that s/he have one too ... and also admiting that s/he is surviver from crash, that Minthara was ordered to kill ...
And she should believe you, bcs you say that you "like her"?
As William Turner Jr. would say: "It's only a matter of leverage". There should be a way to put so much pressure on her that she would eventually listen to the main character and could be turned into their cause just like it is possible with Khaga. She deserves at least the same treatment.
I would welcome more possibilities with a character who has good potential and a very good voice acting on top of that.
That is completely different situation ... with Kagha whole groove stand with you ... with Minthara its you vs. everyone else in radius of few dozen meters. :-/