- "He appeared to be about sixty. Clipped graying hair, lined face, body thickening with age, clearly not that of an outdoorsman or athlete. He wore conservative Earther clothes a generation removed from the historical fashions of the parading teenagers that Miles had enjoyed in the shopping arcade. He might have been a businessman or a teacher, anything but a hairy terrorist. Except for the murderous tension. In that, in the coil of the hands, flare of the nostril, iron of the mouth, stiffness of the neck, Ser Galen and Duv Galeni were as one."
- ―Miles' first meeting with Ser Galen[src]
Ser Galen was a Komarran and a member of the Galen Family, once a powerful oligarchy on Komarr. When his sister Rebecca Galen was killed in the Solstice Massacre, he formed a terrorist group and pressed his two sons, Duv Galeni and an unnamed older one into it.
About the time Miles Vorkosigan was four, the Komarran Revolt began; Ser Galen was a major figure in the resistance. As the Revolt began to fail, Galen began to seek other ways to defeat the Barrayarans, particularly Aral Vorkosigan, the "Butcher of Komarr." Towards this end, he devised a baroque plot to replace Aral Vorkosigan's son with a clone programmed to kill Aral Vorkosigan and as many high-ranking Barrayarans as possible. He acquired a tissue sample of Miles Vorkosigan and left Komarr for Jackson's Whole to set up his plot. To conceal his leaving, he faked his death by means of a large bomb that actually did kill his older son. Upon arriving at Jackson's Whole, he ordered the creation of the clone from House Bharaputra; thus Mark Vorkosigan came to be. He then left to live on Earth among a group of expatriate Komarrans.
When the clone was full-grown, Galen collected him from the Bharaputrans and began training him to replace Miles Vorkosigan. Galen was eventually killed by Mark Vorkosigan.