Orisin Dever was a Bajoran man and a Major in the Bajoran Militia.
In 2380, Colonel Jalas Dren assigned Major Orisin, considered his best investigative officer, to investigate the disappearance of Rebecca Sisko and locate Radovan Tavus, her kidnapper. Jasmine Tey assisted Orisin and his team and Rebecca was successfully rescued in Talveran Forest. (DS9 novel: Original Sin)