Erin’s death in Midnight Mass was one of the most upsetting and surprising because it really seemed like she would be the one to get out, but it was teased 5 years ago in Hush. Midnight Mass has been a passion project in the works for Flanagan that he began pitching to television production companies way back in 2014, and it finally came to fruition through his partnership with Netflix in 2019. Flanagan had several ideas for Midnight Mass’s story either becoming a book or movie and finally decided on turning it into a miniseries for Netflix.
Truly demonstrating how personal Midnight Mass is to Flanagan, he included it in book-form as an Easter egg in two of his previous films. Before it actually became the vampire Midnight Mass series for Netflix, Flanagan most recently included it as a book in his 2017 Netflix movie Gerald’s Game. In the movie, Carla Gugino’s character briefly reaches for the book and throws it at a dog. Aside from its minor appearance in Gerald’s Game, Flanagan used it as a significant aspect of Hush (2016), in which it served as the book written by the main character Maddy. As Maddy is seen writing different endings for the book, discussing characters with her neighbor, and contemplating plotlines, she actually teases one of the saddest deaths in Midnight Mass’s TV show.
While only two Midnight Mass characters end up getting out of the series alive, the deaths for the other characters were heartbreaking in the last few episodes. Serving as one of the main characters, Erin Greene almost gets out alive in the finale as she helps Warren and Leeza escape, only to be attacked and killed by Midnight Mass’s original vampire monster. It was extremely surprising when the vampire attacked her, but Hush had actually prepared fans for this moment. An early scene in Hush shows Maddy’s inner thoughts of how to properly end Midnight Mass’s story, including whether to kill Erin: “Erin dies. Can’t kill Erin. That would piss 'em off. Didn’t set it up properly.” With all of the monologues about death between Erin and Riley throughout Midnight Mass, it appears Flanagan figured out how to set it up properly without pissing off fans.
Since only Riley, Erin, and Father Paul are revealed as main characters for Midnight Mass in Hush, it’s interesting that Flanagan teased the character death that was most surprising considering Riley and Father Paul died and turned into vampires much earlier in the series. The same scene also reveals that Mike Flanagan had the idea for how Erin would die in place 5 years ago, with Hush briefly showing Maddy's manuscript page that appears to describe the scene in which Erin is having her blood sucked by the vampire and launches into her inner monologue about death. Maddy has 7 endings that she’s working through for Midnight Mass, which are likely all of the ones that Mike Flanagan was actually contemplating throughout the past five years in real life. The ending in Midnight Mass’s TV show is absolutely heartbreaking and powerful, especially through Erin’s death, so Flanagan likely realized the one he teased in Hush was actually the best one to land on.
Aside from the major reveal of Erin’s death, the Midnight Mass book in Hush also teases Riley Flynn’s early nightmares about the girl he killed in the drunk driving accident. Another page of Maddy’s manuscript details the glass shining from Tara-Beth’s head on the road in Midnight Mass’s first scene and the fact that Riley always sees her when he lays down at night. It’s also ironic that Kate Siegel’s character Maddy is the one stressing over the fate of Erin’s character, and Siegel ends up playing Erin in Midnight Mass.