Sdan's heritage was a mixture of Human, Orion, Romulan, Vulcan, and, he joked, Aldebaran shell-mouth for stubbornness. His great-grandfather was a Human man, a trader who married an Orion woman, and began a successful hybrid line, with Romulan and Vulcan following. They lived within the Federation. Sdan's ancestors were intelligent, producing scholars, scientists, mathematicians, and doctors. They were also prolific, and Sdan had three brothers, five sisters, and uncounted cousins, all some variety of scholar.
Sdan, however, was the odd one out, apparently being the throwback to his adventurous great-grandfather and hating to study, though he was a skilled mathematician, expert in communications, and otherwise talented with technology. He didn't fit in with either his family or the Federation, for his mixed heritage, love of adventure, and dislike of rules, though he had no criminal record within the Federation. Thus he became a mercenary and joined the Silver Paladin's band of ethical mercenaries and freelance freedom fighters, working for Adrian Dareau.
He and the rest of the organization were based at Rikan's castle, Warrior's Rest, on the planet Treva in 2364 where he aided their rebellion against President Nalavia. Sdan and Poet kidnapped Lieutenant Tasha Yar from the Presidential Palace, stole the USS Enterprise-D's Shuttle 11 from a Trevan hangar, and brought both to Warrior's Rest. Sdan later worked to get a message to the Enterprise through Trevan jamming. When the team plotted to replace the Riatine drug with a placebo, Sdan helped borrow vehicles and disable or trick military surveillance. When Nalavia's forces later assaulted the castle in response, he helped fight off her soldiers, and later flew a flyer against their air forces.
Sdan appeared mostly Vulcanoid, including angled eyebrows and pointed ears, though his eyes were blue. He acted much more like a Human, dressed casually, and had an Orion's sex appeal. He was capable of performing a Vulcan nerve pinch. (TNG novel: Survivors)