When the march on the Tower of Guidance begins, Sothe knows his place is at Micaiah's side.Read here on AO3.
But Micaiah sends Sothe with Tibarn's army instead, to watch over Pelleas there.
Tibarn, the man who's threatened to kill Sothe once before. Tibarn, a man Sothe doesn't much respect or like. Tibarn, who is not Micaiah.
And also: Tibarn, the man that Sothe keeps having weird dreams about, ever since he threatened to kill him.
Sothe/Tibarn/Reyson, ~10k words.
( spoiler-y author's notes )