My Sparkling Misfortune (The Lakeland Knight series, #1‪)‬

Lord Arkus of Blackriver Castle readily admits that he is a villain and sees no reason why it should stop him from being the protagonist of this book. After all, Prince Kellemar, an aspiring hero, has defeated him in a rather questionable way. Bent on revenge, Arkus attempts to capture a powerful evil spirit who would make him nearly invincible, but a last-minute mistake leaves him with a Sparkling instead—“a goody-goody spirit that helps heroes, watches over little children, and messes up villains’ plans.” Bound to Lord Arkus for five years of service and sworn to act in his best interests, the Sparkling is not easy to get rid of, and of course his understanding of “best interests” is quite different from what Lord Arkus has in mind.