Karellen is an Overlord who communicates with Earth on behalf of his people. He shows an interest in Earth and seems to try to understand humanity. However, his interest in Earth is limited to his mission; he does not have true compassion or caring for any humans, even though he "salutes" Earth after it has been destroyed.
Rikki Stormgren is the Secretary-General of the United Nations, and in that capacity, he meets regularly with Karellen to discuss matters related to Earth. While Stormgren is initially in favor of the Overlords taking control of Earth, he comes to see that they are not as forthcoming as he had thought, and he becomes curious about their true nature.
Jan is one of only a few people to question the Overlords' purpose and who feels hindered by their presence. He wants to explore space, but all space programs were ended by the Overlords. As a result, he is single-minded in his desire to achieve his goals, which prompts him to risk his life to learn something about the Overlords' past.
George is a playwright, and when he struggles to pursue his career in mainstream society, he and his family move to New Athens, an artists' colony. There, George begins to see the Overlords in a religious light after his son is saved by a phenomenon for which he believes them to be responsible.
Jean is married to George and goes with him to New Athens, along with their children. Unlike many others, Jean has always been reluctant to embrace the Overlords, and she shows sensitivity to what humans would call paranormal phenomena.