Kyubey is the cutests ball of evil and suffering to ever grace the Route. He is an Incubator, an alien-cat-demon-hivemind-thing bent on filling the world with magical girls.
／人◕ ‿‿ ◕人＼ Contract?
Kyubey enjoys making magical girl contracts wherever he goes, and Route 50 is no exception.
Kyubey made his first appearance on the Route when infiltrating the Skyvoice and offering a contract to MysteriousVaporeon, who started shooting at Skyvoice. Kyubey interpretated the bullets as confirmation of the contract, turning MV into a magical girl. MV later escaped the contract through cloning technology, labeling his magical contract self "FeMV."
Nepeta's connection with Kyubey is unusual. Rather than being a contracted magical girl, Nepeta appears to have been assimilated into the ranks of the Incubators in order to aid Kyubey in making contracts throughout the Route.
Sparkleaf is known to have a "magical vixen" form. Thus far, he has said that he has no contract with Kyubey. However, in real life, he is known to be stalked by two mysterious white cats that Fexible has identified as Incubators.