As previously mentioned, arcats are cats with magical abilities, of which Jammy is not a good example. So, here's Cerus. He's exceptionally talented - while other arcats usually practice some specific chosen type of magic, he seems to effortlessly control electricity, water, fire, sometimes other elements. Or at least it seems that way.
Cerus is a spirit medium, he's got the rare ability to see ghosts and control ghost magic. And pretty quickly he picked up on te fact that desperate souls with unfinished business are indeed great business partners. And if Cerus knows anything better than ghosts, that would be business. So, at any time, he has at least 3 ghosts bound to his tail (usually invisible, + he ignores them a lot, especially around the living). He's trying to find and solve their unfinished stuff. They let him use their magical powers. Everyone benefits, in a way.
But that's just a side gig. Cerus is employed by the queen of Arcatia, it's hard to tell what his exact position is, but he does a variety of things - passes along important messages, digs through the library, sometimes even represents Arcatia internationally.
