Fleming has been librettist and lyricist on "Crystal Balls" (Compact Opera/Sadler's Wells, London), "The Ninth Wonder" (Sydney Theatre Company), "Tess of the d'Urbervilles" (Savoy Theatre, London and UK tour), "Accidental Miracles" (WAAPA/Sydney Theatre Company/Cameron Macintosh), "Satango" (Griffin Theatre Company/Riverside Theatres/Vegas Theater Company), "Ripper" (Ensemble Theatre), "Laid in Earth" (Queensland Music Festival) and "The Merry Widow" for Opera Australia, West Australian Opera, Opera Queensland, State Opera of South Australia, and "Whiteley" for Opera Australia. "Whiteley'’ was nominated by the Writers' Guild for an AWGIE award for Music Theatre 2020 and an International Opera Award for Best New Work 2020.