Viconia is too big of an opportunity to pass when Shar seems to be a major player in BG3.
I definitely don't want these legendary BG2 characters as mundane companions. That would shrink them to the level of Gale, Lae'zel &co where they don't belong at this point. They can't really be villains either unless you can choose to side with your old pals. Their part in the story should be an unexpected hero who saves the PC's when things are looking hopeless. Show up with a display of power when you're about to get killed by a vastly superior enemy. For reasons that can be selfish, heroic or political. And then they disappear as quickly as they appeared before things get too mundane. That would make a great scene, appropriate for their legendary status.
