London said it himself. He described White Fang as a companion piece to The Call of the Wild and set out to write its exact opposite: where Buck is a domesticated dog who reverts to the wild, White Fang is a wild wolfdog brought into domestication. The mirroring is deliberate all the way down. Both books move a canine protagonist across the same Klondike, by the same method of showing thought without granting speech, and each ends where the other began. Not filed same_universe: there are no shared characters and no continuity, just one author answering his own book.