At Nite by Lilo Quie

Cat familiar and smart aleck Australian Midnite has been stuck as a cat for years, traded from human to human dabbling in the magical underground. When a new drug, stardust, saturates the market, Nite knows he needs out, but he’s bound by a collar and helpless. They may have taken his claws, but they’ll never take the sass.
Rexford Redsky, probationary covenmaster of Red Sky has been dealing with humans dabbling in mage business for too long, in between bouts of cleaning up the messes left behind by the mass deaths of his kind. Families destroyed, covens burned to the ground, Rex is left with a little boy who nobody wants to claim. When a little black cat decides his leather jacket is now his home, the key to stopping their deaths is at hand.

It started with an idea, an explosion in my mind. “Mages on motorcycles.” I couldn’t get the image out of my head of a sassy little black cat riding in his owner’s jacket cracking jokes that humans can’t hear. When someone asked me to describe my book, badly, in one sentence it all came together. “Mages on motorcycles getting raptured after snorting their kind’s remains.”