Juel Ducane was a Human male serving in the Federation Starfleet in the 29th century as first officer of the USS Relativity (NCV-474439-G) under the command of Captain Braxton. During the Relativity's encounter with the USS Excalibur in orbit of Haresh in 2374, Braxton ordered Ducane to target weapons on Excalibur and disable her in order to stop Captain Mackenzie Calhoun's interference during a Redeemer attack on the planet.
Ducane was still serving as Braxton's first officer when Seven of Nine was transported to the Relativity via temporal translocation. Ducane was later forced to arrest Braxton when it became clear that Braxton would, at some point in the future, travel back to the 24th century and attempt to destroy the USS Voyager in 2375.
He was subsequently promoted to commander. On December 4, 2381, Ducane stopped a retroassassination attempt on Federation President Nanietta Bacco in Château Thelian, the President's official residence in the Loire Valley in France. He recruited three different versions of Bacco herself to assist him. While one of the three was killed in the attempt, the other two survived and eventually underwent temporal integration. Bacco expressed her unhappiness about how the Starfleet of his era tries people for crimes that they have not committed yet.Later in his personal timeline, Ducane traveled back to February 2382 as a combatant (several times over) in the Temporal Cold War's "hot spot" during that era. He expressed disgust at civilians having jurisdiction over time travel in the 31st century in the form of the Federation Temporal Agency. His strong dislike of Temporal Agent Jena Noi, likewise from the 31st century, appeared to be mutual.