Originally Posted by Vamathi

Previously I was also honestly looking at possibility of Sthrad having something to do with this (Barovia is in Domains of Dread so Shadowfell).
Volo (was there for 99 dragons, might be why he can't shut up about them), Jander Sunstar, Minsc and possibly others were in Barovia.
- WotC also dug out Ravenloft character Jander Sunstar for BG: Descent into Avernus, which doesn't make much sense, until you read that he was a vampire and had a past, that could be what Astarion is recalling in his 'dreams' and that is sort of playing out around us, in a twisted way (slavery, Silvanus grove, that supposedly made him mortal elf temporarily, feeding on animals and preying on sleeping bandits). He also has a history with Sthrad where he attempted to kill him. But he was supposed to die in BG: DiA? Well, yes and no - 'his body crumbles in graceful release'. Listen to what Chris says here.
If you want to know more about where I am coming from please take a look at Shadowfell. I also recommend this video. Shadowfell was just recently moved by Shar and it's supposed to echo in a similar way than Feywild.



I wouldn't believe into Jander=Astarion ( or close to), because Jander is portrayed as a character of firmest morals, capable of stopping even the evilness of the undeath and not losing faith even in Ravenloft and Avernum; Astarion is a survivor, instead.

Other symbolism you've mentioned is too unstable as a theory for me personally, but interesting nonetheless (spiders and Minthara especially so).