Lieutenant Commander Calvin "Cal" Hudson was Starfleet's first attaché to the Federation colonies in the Demilitarized Zone in 2370. Hudson and Benjamin Sisko were close personal friends. They graduated from Starfleet Academy together, and later served on Pelios Station. He was married to Gretchen Hudson, who died in the late 2360s.
Assigned by Starfleet as the attaché to the planets in the Demilitarized Zone, Hudson was actually an influential leader of the Maquis resistance group. He used his Starfleet position to secure intelligence and supplies for the rebels. Sisko uncovered Hudson's secret in 2370, during the investigation of the explosion of the Bok'Nor and the kidnapping of Gul Dukat. (DS9: "The Maquis, Part I", "The Maquis, Part II")
In the Pendragon timeline, the Jem'Hadar never invaded the Alpha Quadrant, and thus Hudson did not die in 2373. Instead, he, along with Eddington, became one of several Maquis cell leaders to broker an agreement to aid Starfleet against Admiral James Leyton during the Federation Civil War. (PDN: "The Good Fight", "L'Morte d'Maquis")