Hearts on the Table by Susan Metallo

In 1915, Violet Farris, a seventeen-year-old half-English, half-Sicilian feminist and skilled card player, flees with her transgender twin brother, Seb, when their father plans to marry them off. A U-boat sinks their ship, and Violet washes up alone on the enemy-held Dalmatian island of Illyria. Disguised as a boy, she works for Teo, an anti-war landowner's son, delivering his love poems to Olivia, but Olivia is drawn to the disguised Violet while Violet falls for Teo. A retelling of Twelfth Night with queer, trans and neurodivergent characters, alternating Violet's narration with verse chapters from Olivia's autistic sister Faustina, a musical prodigy whom a cruel cousin plans to have committed.