Many classic works of science fiction and fantasy imagine a hostile, superhuman invader as a catalyst for unity among human beings, as a divided humanity comes together to fight a common enemy. The angels in Angelfall appear to be just such a hostile force—destroying cities and herding people into camps where they suffer forced labor, torture, and death. However, their presence creates at least as much conflict and division as it does unity and cooperation between humans. Penryn meets many other human beings throughout the book, both hostile and friendly. Very few are purely sympathetic; many act selfishly, asserting power over her or others or prioritizing themselves and their own gain over even the lives of others. Even characters like Obi, one of the more heroic of the rebels, demeans Penryn and enforces a heteropatriarchal society among the survivors for no apparent reason except personal power or biases. Despite the selfishness and competitiveness of many humans, however, Penryn learns that she must rely on others if she is to survive. The book suggests that humanity, too, will have to learn to prioritize communal solidarity over individual power.

Penryn is rarely alone for long, and she depends on others to ensure her survival.