Canonically Viekang survives and either kills Gorion’s Ward (Abdel Adrian) and becomes the Slayer or Abdel kill him and becomes the Slayer. Either way, the player party in the campaign Murder in Baldur’s Gate kills the Slayer, and this kicks off the events of that campaign.
I‘m hoping that none of this is mentioned in BG3 so I can just ignore it.
Ah I did not know about the Murder in Baldur's Gate.
I know its silly to think so but I prefer to pretend that Abdel Adrian does not exist and my Bhaalspawn is chilling happily on the Planes.
I do like the fact that any mention of Gorion's Ward in the game is very ambiguous right now, just that they existed, but who they were was left out. I can only hope it stays that way.