A cheshire is different from a house cat in only two ways: it is completely hairless, and its skin shifts color like a chameleon. Cheshires are therefore extremely efficient hunters. On many habitats, such as Valles-New Shanghai and Extropia, they are prized for their skill in reducing pest and vermin populations. On many others, they are banned, for fear of their effects on carefully cultivated ecologies.
The first cheshire was a gift presented to the daughter of a biotech executive. The cat bred with other house cats, and it was discovered that someone in the genetic engineering department had not done their due diligence: the chameleon skin trait was both heritable and dominant. Within the decade, cheshires seemed to be everywhere.
Some Triad members in Valles-New Shanghai have been experimenting with the use of trained or goaded cheshires as spies. The cats are everywhere in the city, after all, and by their nature are rarely noticed. Pax Familia may have beaten them to the punch, at least judging by the spate of Nine Lives members who have been assassinated by small, venomous claws.
As smart cats, plus chameleon skin.
Based on the cheshires from Paolo Bacigalupi's excellent The Windup Girl.