Infernal Frequencies

Luna Cross can hear the end of the world coming. It's broadcasting on a frequency only she can feel.

Behind the alias Midnight Architecture, Luna is the most sought-after mix engineer in Los Angeles — and nobody knows her name. That's how she likes it. Her synesthesia has been called a disorder her whole life. She calls it armor. Then a signal starts bleeding through the city's airwaves, driving ordinary people to violence, and Luna is the only person in LA who can trace it to its source.

Raziel was the Angel of Mysteries — four thousand years old, keeper of secrets that end civilizations, fluent in vintage synths and dead languages. He's had one rule since the last human he loved died because of what he shared: never again. Then Luna walks into his condemned Hollywood tower hearing things no human should survive hearing, and every wall he's built starts coming down in the space between heartbeats.

The demon behind the broadcasts knows Raziel intimately. Knows exactly what he did. And plans to make Los Angeles pay for it — one perfect, catastrophic show at a time.

She wants someone all in. He's spent eighty years proving he can't be. The city doesn't have time for either of them to be wrong.

Tropes & content include: fated mates · grumpy x sunshine (he's the grump) · secret identity · he studied her work before he ever met her · bisexual hero · MMF ménage (no jealousy, all consent) · ex turned enemy · found family
Steam: explicit, high heat, M/F and M/F/M. 18+. Content notes at author site.

HEA: yes — no cliffhanger. Reads as a standalone.
Book 2 of The Fallen Response Unit: Fallen angels running the supernatural emergencies no one else can survive.