If the way Iris and Roman’s unseen correspondence—those typewritten letters slipping through a wardrobe—made your heart ache, you’ll love how The Undertaking of Hart and Mercy uses enchanted mail to spark an anonymous, soul-baring epistolary romance between a grumpy marshal and a sharp-tongued undertaker. Like when Roman realizes the person behind the letters is the rival he misjudged, Hart and Mercy discover they’ve been confiding in the last person they expected, and it’s utterly swoony.

If you were hooked by Iris and Roman’s newsroom rivalry ripening into tenderness as their letters reveal who they really are, The Night Circus delivers that same electricity. Celia and Marco are bound as competitors, yet their covert notes and collaborative creations turn opposition into intimacy—much like how Iris and Roman’s barbed banter melts once their words bridge the distance between them.

If the divine conflict between Enva and Dacre and Iris’s mortal vantage point on a god-wrought war gripped you, Gods of Jade and Shadow offers a similarly alluring dance with divinity. When Casiopea strikes a bargain with a Mayan death god, she’s pulled into a perilous journey where the whims of immortals collide with human hopes—echoing the way Iris navigates the fallout of battling gods while clinging to love and purpose.

If Rebecca Ross’s poetic cadence—those tender, letter-laced chapters amid the thunder of Enva and Dacre’s war—swept you away, Strange the Dreamer will cast the same spell. Taylor’s language shimmers as scholar-dreamer Lazlo and mysterious Sarai reach for each other across a scarred, god-touched city, capturing the same aching beauty you felt when Iris and Roman’s words lit up the dark.

If you loved how Divine Rivals keeps the focus tight—on Iris and Roman’s bond growing through letters, trenches, and quiet confessions—Emily Wilde's Encyclopaedia of Faeries leans into that same intimacy. In a remote village, Emily’s field notes and day-to-day frictions with the maddeningly charming Wendell blossom into warmth and devotion, echoing the tender, close-quarters connection that carried Iris through the front and back again.