I chose Mary Hoffman's Stravaganza series to fancast because, aside from Harry Potter and Disney, it made up a huge part of my childhood. If you're not familiar with the series, it's half set in modern-day London, and half in a parallel world called Talia very similar to Renaissance Italy but with some marked differences. Other characters I chose to fancast are one of the English Stravaganti (these are people who manage to travel between the two times/places) called Isabel Evans / Isabella. Most of the characters I fancast belong to the Di Chimici family, kind of similar to the Medicis but they have control over multiple city-states in Talia, and while some members of the family are ruthless and ambitious and are the enemies of the Stravaganti (both English and Talian), others are more benevolent. Filippo Nucci who is a member of a rival family to the Di Chimicis and is involved in a feud similar to that of the Pazzi-Medici one in Florence, and Guido Parola who is a reformed assassin who sides with the Stravaganti.
Sarah Bolger as Beatrice di Chimici | Maria Doyle Kennedy as Clarice di Chimici | Katie McGrath as Francesca di Chimici | Colin Morgan as Gaetano di Chimici
David Oakes as Rinaldo di Chimici | Holliday Grainger as Lucia di Chimici | Jessica Brown-Findlay as Bianca di Chimici | François Arnaud as Filippo Nucci
Georgia King as Isabel Evans / Isabella | Annabelle Wallis as Benedetta di Chimici (deceased) | Georgia Moffett as Caterina di Chimici | Eddie Redmayne as Guido Parola