I do not see the point of questioning my in-lore reasons, but;

  • I knock her out because she is just a victim (which is obvious even in ACT 1).
  • I spare her because that's just my way of doing things.
  • I recruit her because she is the enemy of my enemy willing to join me.
  • And then I find out everything about her.


In any case I never reached ACT 3 so got no clue who Viconia is supposed to be, but lets not spoil parts of the game which are unrelated to Minthara's recruitment.

[Linked Image from bg3.wiki] Minthara's Compendium Of Issues