I've been slowly working through my evil playthrough to score the romance with Minthara and only just recently wiped out the Druid Grove to win her over during the party back at my camp. Boy, the devs sure poured their heart and soul into that rather spicy night with her. I approve!
Funny too how those scenes got finished way before the pc's own companion romances!
Anyway, I do like all of the speculations herein about Minthara's conflicted nature and while I highly doubt that she will be added as a full companion during the completed version of the game, I would very much like that to be the case.
Why not? I'm pretty sure Halsin will be our companion, but if you choose evil way, then Minthara should be with you instead of Halsin.