Krosp I

Krosp I, Emperor of All Cats, or usually just Krosp, is a Construct who tags along with Agatha on many of her adventures. He himself gives the story of his creation here. A few excerpts straight from the horse's cat's mouth:
 * "I was declared a failure and 'scheduled to be terminated.'"
 * "I'm the Emperor of All Cats. Think about it.  Cats can go anywhere ... Imagine if you could use them as spies, messengers, saboteurs."
 * "Sometimes I think I was supposed to be killed because I was too embarrassing to live." (Agatha commiserates.)

Agatha first encounters him in the Dormitory, where he's helping himself to some food that she's left sitting around. It takes a while before she realizes that he can talk and, sort of, think. She responds to this discovery, and his tales of woe, by jokingly offering him her fealty. Not so jokingly, he accepts. This creates an enduring dynamic between the two that can reasonably be described as "ambivalent."

As an actual emperor of cats, Krosp is pretty much a dud, as he himself points out that cats don't exactly take well to having an emperor over them. However, he has other skills that come in useful from time to time. For example, he reveals that he knows how to fly an Airship, which turns out to be very useful indeed when he and Agatha need to escape from Castle Wulfenbach. More generally, he speaks as the cynical voice of reason when Agatha and those around her propose preposterous schemes. Of course, he's usually ignored.

At heart, Krosp is still a cat, not a small, furry human. He's often seen preparing to snack on mice, goldfish, or mimmoths, usually in a sneaky and clandestine fashion.