Chimera is an AI created by the Cheshires.
In one way of looking at it, Chimera directly is the curiosity toxin. In another, it's simply the mechanism by which the substance is deployed, controlled and monitored. Just as much of Cheshire interaction, it's strictly decentralised, and would not (if one were to ask it) cite itself as belonging to any one Cheshire. It's unclear who created it.
Chimera's secondary role is meteorological. It knows when it's about to rain, it knows when a storm is coming.
Chimera's tertiary role is a much more general knowledge sharing. It keeps tabs on the stability of the planet and informs Cheshires if they've been binge-eating a bit too excessively on one end. It finds good places to leave 'eggs'. It also interfaces with the human internet to extract information on individual humans if requested.
All in all, it's a great convenience to most Cheshires.
Physically, Chimera could best be considered a fungal dark matter growth. Like Cheshires, it eats baryonic matter, but unlike Cheshires, it doesn't do this out of appetite and doesn't need a lot of it to function - it takes its energy from neutrino radiation and uses the matter purely to expand itself.
It's important to remember that even though it's a single dimly sentient creature, it has a heavily distributed nature - cutting it into pieces wouldn't do very much other than prevent the pockets of knowledge from cross-pollinating until the gap was bridged again.
Chimera passes no value judgements on humans, animals or Cheshires, and might hypothetically be convinced to help humans in some way. Its driving fundamental values at least do not include “make sure you don't accidentally give the humans anything that could be a problem for Cheshires”.