Learned Darian is a servile residing in the Peaceful Valley. She counsels the other serviles on Sucia Island, and in more peaceful times she helped to broker truces and agreements between the different sects. She also harbors a group of serviles who want nothing to do with the warring sects, giving them a place to live simply, away from the fighting.
By the time you reach her, the sects are not negotiating with one another, but they continue to have great regard for Darian. As such, you can ask her to use her influence to increase your standing in the eyes of one of the sects, regardless of your prior words or actions.
Learned Darian continues her peacemaking in the second game, establishing a similar haven for runaway serviles near Barzite lands. She is somewhat worse for wear; her attention slips sometimes, and she lost a hand to a rogue fyora during the escape from Sucia. Still, she maintains the influence she once had, but only over the two servile sects in the mountains.
As before, she can intercede once on your behalf to spread word that you are either loyal to Shaper ideals or willing to embrace servile freedom. She is also able to make one of the artifacts in the game; if you give her a perfect glaahk scale, a set of demon claws, and the skin from a battle gamma, she will make you the Emerald Breastplate.