Relationships are not static. We fall in and out of love; children grow up, and their connections to their parents stretch and change accordingly; colleagues become friends or enemies or some strange mixture of both. Relationships between characters in science fiction and fantasy are no exception. Indeed, SFF devices like shapeshifting, time travel, and alternate universes allow writers to push the boundaries of how much a relationship can change while still technically involving the same two people.
In my debut novel Meet Me in Another Life, Thora and Santi encounter each other again and again in different realities. Initially, their memories reset every time, forcing them to relate to each other as friends, lovers, enemies, adopted family, and more. Later, as they begin to remember, the novel asks what it would mean to try and reconcile all those versions of a relationship into one. The book owes a debt to protean SFF duos I have loved: characters whose connections with each other cannot be contained by a single timeline, or a single pair of selves. Here are five examples.