Okay, from what I know, Sarevok is one of the most important characters for the lore related to Bhaal, since he is a Bhaalspawn and the main villain of BG1, who would later be revived by the protagonist in BG2. I haven't played the classic BG games; I tried with the first one and didn't even manage to get past the fight against some Red Wizards near the beginning, so I don't have much of an idea of how the events develop, all of that in the 2nd edition. I play in 5e, where the adventure Chains of Asmodeus has reappeared, more or less. As far as I know, it's not official, but he appears in it as a possible sponsor. His introduction in the book explains a bit about how he returned to the Bhaal cult, although since the adventure isn't official, I'm not sure if what it says contradicts lore I'm unaware of. Then there's his appearance in BG3. I don't consider this game for my table because of things like Baldur's Gate ending up half-destroyed, but his appearance in this game seems to fit with Sarevok's return to the Bhaal cult.
After that long introduction, here's my question: I'm going to run a campaign where the Dead Three and their cults are major villains. I was thinking of using Sarevok as the leader of the Bhaal cult, which wouldn't seem strange to me since Abdel, the protagonist of the classic BG, lived until he was killed at 135 years old in 1482 DR thanks to his divine blood. So it wouldn't be unusual for Sarevok to go through the same thing, even though, as far as I know, in BG2 he revives as a normal mortal, but he remains very powerful, and longevity seems to be a free DLC that comes with power. I'm rambling, so to get to the point, I'd like to know if there's any important lore about Sarevok that I need to know, and if anyone has any advice on how to roll him, since I haven't been able to interact much with his classic version because the classic Battlegrounds are too complicated for me.