He became the Royal Guard in other to bring Marali and Mirith together as cooperating cities, keeping the intention of returning to the north at some point later. In the meanwhile, though, Marali was sieged by the Twins in 426, and Nyatha Vaup succeeded in command, instead of General Valencia Falvo. Falvo would have been the natural new Commander, after the death of Maximus Adams and Adelphius Kang during the siege.
As Royal Guard in Mirith, or in close collaboration with Zexe even before that, Birek was involved in several important events in the history of Oberin, e.g. working with Marthonis on the spell to release Alastor from the Eye, or the war against Lancaster, by whom he was captured and briefly kept in Andris. It is also know that he was a student of Beleth and has some knowledge of Black Magic.
After resigning from his Mirithian position, however, Birek never returned to his former military structure. It is known that Vaup sent out scouts in order to find him and bring him back to the fort, but he refused to return before finishing off an unknown business.
Birek was seen again in public during the Red Moon of 432, together with the healer Altaira Mei. They helped an enormous group fighting an Abyss Dragon, who had came out of the Rift. At that time, a reference to a certain "Valencia" who would be waiting for the couple was made, leading people to believe that the three Maralians are hiding together in the woods, perhaps plotting to take the power of Marali in their hands again. But that belongs to the realm of speculation, and nothing has been heard of any of them since.