 What is Trella's relationship to Dom Blessing?
Trella had the desk clerk call a cab to deliver the unconscious Motwick to his home. Her employer had impressed upon her that her mission was confidential, but surely Dom Blessing could not object to Dr. Mansard's son knowing about it. All these things had happened before she was born, and she did not know what Dom Blessing's relation to Dr. Mansard had been, but it must have been very close. Dr. Mansard and his wife had disappeared into the turbulent atmosphere of Jupiter just after his invention of the surgiscope, and it had been developed by Dom Blessing. Blessing would, of course, be happy to learn that a son of Dr. Mansard lived, and would see that he received his rightful share of the inheritance.
 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.