Sergeant Katsaros was an Imperial Security guard charged with watching Cordelia Vorkosigan's grandchildren during Admiral Jole's birthday party. When ghem Soren, a Cetagandan who'd put up a Discernment Garden display for the party, was attacked by drunk military men, the local security forces were disinclined to act. However, her young charges, Alex and Helen Vorkosigan, rushed to his aid, ending up in a fight with them. She stunned one of the men, and local security arrived to help. She then contacted Cordelia to request her assistance in dealing with the resulting situation.
She also was the first to arrive to assist Jole after he was burned shortly afterwards.
- Gentleman Jole and the Red Queen, chapters 15, 16