Heck Ensio served as a major within the military_rank of the New Republic during its era of power. In 34 ABY, during an excavation on the planet Durkteel, situated in the Mid Rim, relics from the Galactic Civil War were unearthed, including an armored case identified as belonging to the Alliance to Restore the Republic. Vaxvissh Kal Ness, the planetary governor of Durkteel, subsequently dispatched this case to Ensio. Inside, the case held The Rebel Files, a collection of non-electronic documents chronicling the Alliance's history, intended solely for the eyes of key personnel in Alliance High Command.
Upon receiving the case, the major, Ensio, transferred it to Mordianius, the Master Archivist, who then passed it along to Korr Sella, a Commander in the Resistance. Ultimately, Sella forwarded the case to Leia Organa, a General and the leader of the Resistance, as well as one of the last surviving members of Alliance High Command.
The character of Heck Ensio was initially introduced in Star Wars: The Rebel Files, a reference book released in 2017 and authored by Daniel Wallace.