Actually Savarok trying to be the Highlander sounds about right. It's actually a very cool way to think about it.
Alas without evidence tis no more than fancy.
it is

Here is the post from one of Sarevok's concept artist, admitting that he was a rip-off from Highlander's Kurgan:
https://www.deviantart.com/uncannyknack/art/Sarevok-359439963This proves the highlander was an inspiration for Sarevoks design, not that Sarevok trying to be the highlander is the plot line of BG1

Try again.
@robertthebard
Don't type fast at me if you don't see a reply until tomorrow because I have actual children I need to go take care of. You are welcome to PM me as well if you would want more immediate attention.