Maybe Shadowheart is the "main character" of the game for the most part. It's just that we have such an incomplete picture that it is hard to say.
If it does turn out that SH is the main character of the game, then in my game I can guarantee that I will kill her off as soon as I first meet her. In an RPG the PC is who should be the main character of the game. If that rule is ignored in BG3, I will remedy that defect in the game by killing her off as a matter of principle.
