Becoming Effrijim by Katie MacAlister

A wounded demon in Newfoundland dog form, a mysterious bestie, and a thirst for vengeance so strong it almost warrants drinking from the toilet. Almost.

Effrijim, demon sixth-class, and well known Newfie-about-town is back with excerpts from his diary detailing his origins, how he was kicked out of not-Heaven and sent to not-Hell, and how a plan for some truly spectacular revenge draws in everyone from one of the most powerful beings in the Otherworld to the lowliest of demons.
Filled with Easter eggs sure to delight fans of the Aisling Grey, Guardian series, this Otherworld short story takes readers back to where it all began.