Seeing as AMC has got a taste for spin-offs, what with Better Call Saul as well as an impending prequel to The Walking Dead, theres no reason Preacher couldnt do something with its spin-offs too. During his trek across America and to the depths of heaven and hell, Ennis also explored some of the book's greatest characters by telling their own standalone stories. Admittedly, some of the spin-offs would be better suited as flashbacks, but for the likes of blood-sucking Cassidy, and the unstoppable Saint of Killers (who would gain popularity as the show progressed), it wouldnt be surprising to see them go solo. Learning the how and why of the Angel of Death and Jesse's vampire mate went from men to monsters would make great viewing that could either occur after, or run alongside the primary show. Its not exactly new for comic book properties to branch off and intersect with one another, so why wouldnt this work just as well?