The time travel bubble in Gary Kloster's “Interchange” is essentially a very fancy backdrop for a study of human nature: Are humans good? Evil? Violent? Selfless? Capable of love? Serene? Able to change? Abhorrent? The protagonist, Lucy, is a victim of domestic abuse and shot the man she loved in self-defence, and she is all of those and none of those. The change to come, the “infection”, is not human, has only one of these traits, and yet may be the future of humanity.