I absolutely do not see Halsin as a companion. His role in the story is NPC leader and mentor, not adventuring companion. There can not be a level 4 "Archdruid" or "First Druid of Emerald Grove". I don't care how cool or hot he is as a character, everyone needs to play the part that's written for them.
The only way I could see him as companion is BG3 level 10+ end game if his circle is destroyed or overtaken.
Counsilor Florrick would make more sense as a companion than Halsin even though she has her own responsibilities as well.
