 What is Trella's relationship to Dom Blessing?
Trella feared she was in for trouble even before Motwick's head dropped forward on his arms in a drunken stupor. A woman could not possibly make her way through these streets alone to the better section of town, especially one clad in a silvery evening dress. Perhaps she could call one of Motwick's friends; she had no one on Ganymede she could call a real friend herself. Trella swung with her whole body, and slapped him so hard he nearly fell from his chair. The dark man moved in on Trella again as Kregg overtook his quarry and swung a huge fist like a sledgehammer. Exactly what happened, Trella wasn't sure. The dark man, who had grabbed Trella's arm, released her and ran for the door. Trella ran to the unconscious Motwick's side. He followed Trella out the door of the Golden Satellite and fell in step beside her. “He and my mother lived on Jupiter until the oxygen equipment wore out at last. Trella could get a cab from here, but the Stellar Hotel wasn't far. Trella had the desk clerk call a cab to deliver the unconscious Motwick to his home. For some reason she decided against telling him that the assignment on which she had come to the Jupiter system was to gather his own father's notebooks and take them back to Earth. Motwick was an irresponsible playboy whom Trella had known briefly on Earth, and Trella was glad to dispense with his company for the remaining three weeks before the spaceship blasted off.
 Trella is Dom Blessing's employee.
 Trella is Dom Blessing's employer.  Trella is Dom Blessing's sister.  Trella is Dom Blessing's employee.  Trella is Dom Blessing's mistress.