Ruul was a citizen of the Romulan Star Empire, a male Romulan serving as officer in the Tal Shiar. Following the death of Colonel Hakeev, Ruul became the de-facto leader of the crumbling remains of the Tal Shiar. (STO - "New Romulus" missions: "Mountain Base", "Secret Shuttle Codes")
Following the colonization of New Romulus by the Romulan Republic, their enemies from the Tal Shiar established a presence on the planet. This included a base in the Mountain Pass of the Vastam Peaks, a mountain range near the Staging Area and city. Commander Ruul was left in charge by Colonel Hakeev. A Kestrel-class was placed on a landing pad at the base and served as shuttle.
When Brea III, the last major holdout of the Tal Shiar, was under siege by Allied forces, Hakeev advised Ruul that the commander was one of the last remaining leaders. Ruul struck a deal with a Hirogen Beta, and a combined Hirogen-Tal Shiar team then defended the base. The Romulans took Republic prisoners. Soon after, the Tal Shiar and their Hirogen mercenaries were defeated by an Allied away team making its way through the mountain pass. They freed the prisoners, gained intelligence on the Tal Shiar from the shuttle and a nearby console, and captured Ruul. Ruul was subsequently handed over to Republican authorities for questioning. (STO - "New Romulus" missions: "Mountain Base", "Secret Shuttle Codes")