The story
He paid a year's rent up front. His only rules were don't ask and don't open his door.
Emma is a painter with no money, so when a gorgeous stranger moves in and hands over a full year's rent at once, she's not about to argue. He only has two rules: never ask about his past, and never open his door. But odd things start happening, and Emma finds out her roommate is a Demon King who's been alive for 900 years and passing himself off as a billionaire CEO. Then an accident ties their souls together in a pact that can't be broken, and they have to act like a couple. The fake relationship starts turning real right as Emma discovers her own origins are even more powerful than his.