King of Hearts: A Spicy, Motorcycle Club Short Read (Outlaw Royales Motorcycle Club Series Book 6)

Name: King of Hearts: A Spicy, Motorcycle Club Short Read (Outlaw Royales Motorcycle Club Series Book 6)
Author: Donna Costello

Donna Costello

Book 6 in the Outlaw Royales Motorcycle Club (Donna Costello) series · Reading order →

SpiceDarkness

How we rate spice & darkness

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Spice & darkness rated — content warnings listed below

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Why we recommend it

A quick, scorching hit of motorcycle-club heat for readers who want their alpha bikers fast and filthy. Short and combustible, it trades slow burn for instant claim — a rough, devoted club brother who decides she's his and refuses to be told otherwise. Perfect for a one-sitting binge when you crave leather, loyalty, and an outlaw who treats his woman like a throne worth defending.

At a glance

King of Hearts is book 6 in Donna Costello’s Outlaw Royales Motorcycle Club (Donna Costello) series; to read in order, start with King of Clubs – A Single Dad, Motorcycle Club Short Read Romance. Spice 4/5, darkness 3/5 — on the lighter side for mafia romance. Among 931 rated mafia romance books, almost none are less dark and 24% less spicy. Tagged tropes include standalone-in-series, instalove and alpha hero. Standalone-in-series is one of the less common tropes in our catalogue. It is about as dark as Donna Costello’s other books on Readark (average darkness 2.8/5). 1 content warning is listed below, hidden until you tap.

Tropes

Alpha Hero Forbidden Romance Instalove Possessive-Obsessive MC Standalone-in-Series

Book details

Published: February 2026

King of Hearts spice level

King of Hearts is rated 4/5 for spice on Readark’s scale: explicit and frequent, meaning multiple detailed scenes, with heat central to the story. Its darkness rating is 3/5: genuinely dark, meaning violence, coercion or captivity drive the plot, not just the mood. How we rate