So with the game release two and a half months away I figured it would be prudent to have a thread where we can discuss questions that aren't about the plot so much as about aspects of setting lore and the background of the story that are unclear.

One thing which I'm really unclear of is a lot of stuff surrounding Elturel. Firstly, I was under the impression that some of the tiefling refugees were turned into tieflings in Avernus because of the infernal energy all over the place. Is that right? Also, how long was Elturel actually in Avernus? Zevlor was a Hellrider, and it sounds like they were working for Hell while they were in Avernus, given a name like that. So yeah, what's the story with all that?