The following is Bethesda's Official Character Profile of S'ratha:
Today S'rathra is suave and urbane, a rich and powerful Khajiit in a world of Men-far from the young suthay-raht that used to run with the violent nomad cats of the Ne-Quin'al plains. After being lamed at the massacre of Stoop Low, he left Anaquina to keep from bringing shame to his tribe, eventually ending up in the far more cosmopolitan Pellitine to the south. For a time, S'rathra ran a lucrative skooma trade out of Senchal port, smuggling sugar into the Empire (becoming, unfortunately, an addict himself in the process). When Cyrodiil strengthened its presence in the Topal Bay, S'rathra left Elsweyr entirely.
He has made Wayrest his port of late, playing the lesser lords of High Rock to his benefit. Though the Empire has solidified the Bretons, there is still a lot of money to be made in the drawing of borders before the provincial laws dry completely. Mercenaries and fixers are in great demand there, and Cyrus and S'rathra have long shared a mutually beneficial relationship- the catman finds the paying parties and the Redguard does the dirty work.
S'rathra's latest assignment for Cyrus is cut short when the Redguard hears of his missing sister. The Khajiit, perhaps knowing all too well the loss of one's kin, provides the money and transport necessary for Cyrus to reach Stros M'kai.