Keeper of the Cob: Backworlds book 1 by Thurston Leigh

Vrx Gnerghal is a ghoul with a family to feed in a world where his kind and their “liberal” dietary habits are frowned upon. With the help of a powerful magical artifact, he stumbles upon a portal to Earth, where the humans are fat, slow and delicious. When a teenager smoking weed in the forest catches Vrx sneaking through the woods with a sack full of fresh meat, he and his friends decide to follow the creature through the portal to the hidden world beyond, and are quickly roped into the machinations therein. They will be stabbed, bitten, transformed, stabbed again and have to put up with a lot of walking as they are dragged through the countryside by a reluctant bounty hunter in her quest to find Gnerghal, kill him, and retrieve the artifact he stole.