Richardson was a Starfleet ensign who served aboard the USS Defiant.
In 2374, Jadzia Dax ordered Richardson to the bridge during the attack on the Dominion sensor array in the Argolis Cluster. Dax wanted Richardson to take over the helm from her and ordered Richardson to find a crewmember to take over tactical and operations as well. Richardson arrived on the bridge shortly after with a lieutenant whose name Dax could not remember. (DS9 - The Dominion War novelization: ...Sacrifice of Angels)