Someone recruited both Minthara and Halsin on Reddit and provided step-by-step approach. Minthara seems to have less content than every other companion though.
I thought, that would not be possible. I imagined, that Halsin would kill her on sight. I guess, you have to just beat her unconscious for that?
No…
You need to save grove by finishing the shadow druid questline which will unveil Kharga. Then, I managed to convice Kharga she is wrong and after finishing the quest she will allow tieflings to stay in the grove. You go to goblin camp and free Halsin and then tell him to stay there in jail and wait for you. Dont interact with Minthara in any way, just ignore her. You kill other 2 leaders in goblin camp (not sure if necessary). Go to Underdark and straight to Act 2. Get to Inn with harpers and interact with sleeping guy to get the quest started.Then to tower where Minthara will be judged and sent to prison. You save Minthara and she joins your party. Then you return for Halsin and tell him about the sleeping guy. He will travel to the inn. You progress the quest from Halsin until he offers to become permanent companion. done
Courtesy of Hawkectid on Reddit. Apparently Halsin and Minthara don’t have any interactions yet, so this is probably a glitch or exploit rather than intentional.
Remember the human (This is a forum for a video game):
