All Gale wanted was for Mystra to forgive him ... and if you play your cards right, he can not just get back on her good side ... but stand as a GOD by her side!
All Astarion wanted was to be free from Kazador ... and if you play your cards right, he can not just get rid of him ... but take the sweetest revenge ever, and become the very thing Kazador was planning and preparing for possibly even centuries!
All Shadowheart ever wanted was to serve Shar ... and if you play your cards right, she can not just finish her mission ... but become chosen one and lead her own Shar temple!
All Lae'zel ever wanted was to be a good soldier for Vlaakith ... and if you play your cards right, she can not just join her army as full grown Githyanki ... but become Ascended! (Put aside what that actually means.)
And finaly Wyll is ... just there i gues.

I dunno, he keeps babling about how he wants to be a hero and he is in the end ... sort of, in every ending ... dunno, i admit i never payed him enough atention to be certain.
But the greatest desire Karlach had was to just live ...
Basicaly humblest of those desires ... and she cannot be saved in any other way than damnation in Avernus. :-/
And she is quite litterally the only follower who can be turned into Mind Flayer, ergo become damned in entirely different way. :-/