Who is Don Solomon Haslam / Suleiman Usman from Flashman's Lady and what is their importance?

Haslam is an enigma. No matter where he goes, he is perceived in the way he presents himself, though no one really knows anything about him. He is sais to be rich, friendly, and generous, taking a particular interest in Flashman's wife, Elspeth. Haslam is married to the Sultan of Sulu's daughter.