The Demon King's Lost Queen

Luna Lynn takes in Orion Vaughn, the Demon King, whose spiritual power is damaged. They make a pact: Luna cares for him, Orion helps her work, while he searches for his Queen. Feelings blossom. Orion notices Luna's touch soothes his condition, making him suspicious of her origins. Luna reveals her true identity as the Queen. Luna opens a company and marries Orion.