- "Hawk-like, Miles decided, was the word for Admiral Oser. Greying hair, a beak of a nose, a bright, penetrating stare, fixed now on Miles. He had mastered the look that makes junior officers search their consciences, Miles thought."
- ―Miles' face-to-face meeting with Oser[src]
Yuan Oser was the creator of the Oseran Free Mercenary Fleet; they advertised themselves as a free coalition of mercenaries, and it was a point of pride that most of the captains of their fleet were "Captain-owners", people who owned their own ships and could leave or stay as they wished.
Miles Vorkosigan gradually took them over in the Tau Verde Ring war; he renamed them to the Dendarii Free Mercenary Fleet. Oser spent the next two years plotting how to take them back over; when he succeeded, he demoted the officers who were particularly loyal to Miles. Miles Vorkosigan returned to the fleet and re-took ownership; Oser was killed in the battle that followed soon after.