Here is my theory:
In the cutscene where we almost come under control of the Absolute it is the weapon that saves us from falling under their control. If Shadowheart isn't around, the articact gets tranfered to our Avatar. My guess is that at some point during act1finale/Moonrise tower, the artefact will protect our currently selected party, but everyone back at the camp will come under the influence of the Absolute. That way that can come back as antagonist - something Larian hinted at and half-hazardly did in D:OS2. I assume they have an idea that they didn't manage to fully realise in D:OS2, and they are giving it another shot in BG3.
I would be absolutely baffled to no end if they actually double down on that AGAIN, especially considering how people have complained that specific element of DOS2 was one of the parts not well received from fans of the game. Personally speaking I didn't hate it nearly as much as others did but I can't imagine a world where they go for it a second time and it working out in any other way reception-wise than how it was received in DOS2.
Without specifically spoiling anything from DOS2(gonna drop a spoiler tag nonetheless), my only real concern is
whether or not they manage to keep the pace of the rest of the game as solid as Act 1 is so far; anyone who's play DOS2 knows that the end of the game feels like some pieces were missing or not expanded on as well as complaints about Arx as compared to the previous Acts of the game. Judging from what I've played of EA, Act 1 feels pretty solid and interesting and I'm hoping to the Absolute itself that Acts 2, 3 or however many we're getting this time are as refined and polished like 1 is-even more so because of just how much of the game hasn't been put under the mass testing of Early Access.
