In the alternate history of April and the Extraordinary World, the Franklin family of scientists attempts to develop an invulnerability serum for the French government, and one of their early successes is an intelligent talking cat named Darwin. Darwin serves as companion for granddaughter April after most of her family is killed or captured, apparently reading to and tutoring her as well. When April comes close to perfecting the serum, Darwin is close to dying from old age. A drop of it revives him, but the transformation is observed by a mechanical rat drone in the employ of some similarly intelligent Komodo dragons. Their attempts to kidnap April and her companions result in Darwin being launched to the moon on a rocket seeded with plants and the invulnerability serum. Darwin is thought lost until decades later, when technology advances to the point where a satellite can be sent to the moon to send back video of a healthy Darwin running towards the camera and declaring his desire to be reunited with April.