In the mirror universe, Ruunek was a Klingon and member of the Klingon Imperial Fleet.
In the 2340s, Ruunek served aboard the IKC Tlhab as the ship's tactical officer. He was responsible for running a comparison that revealed Captain Druja had not actually issued orders for the ship to retreat and had been impersonated. (STA - Mirror Universe- Shards and Shadows short story: "The Traitor")