Barton is the protagonist. He is an EDS pilot. Although he must jettison Marylin from his ship, he does show compasssion toward her. Barton tries to find a way to help Marylin and treats her with senitivity and even tells her she is not a coward. Barton is a good guy who is forced to do a bad thing.
Marilyn is a victim of a bad situation. She must die due to her mistake of selecting an EDS to stowaway on. Marilyn is only 18 but shows maturity by resolving to her fate. She dies a hero instead of trying to make the reader feel sorry for her. Clearly innocent of mal intent, Marilyn is a victim of the laws created for the society that kills her.
Gerry is Marilyn's big brother. He clearly is a loving brother who will be left with a memory of being able to say good-bye to his sister. Gerry does not blame Barton and does not scold his sister for her mistake.