WARNING: The following contains spoilers for Season 15, Episode 12 of Supernatural, "Galaxy Brain" as well as Season 3, episode 2 of Westworld, "The Winter Line."
Supernatural and Westworld are two very different shows. One is a network television show about monster-hunting, angels and demons that is based on traditional Christian theology, as well as a host of other folk tales. The other is a super-serious drama that started as a Western-meets-Jurassic Park-meets-artificial intelligence. As such, given their lack of surface-level similarity, one wouldn't expect to find a common motif between the two. However, there is one: books.
Specifically, books being used to represent people's lives. While it's a symbol that's appeared before in fiction (recently in SyFy's The Magicians), it's not a common one. As such, it appears in two very different ways in Supernatural and Westworld.
In Supernatural, more specifically the Season 15 episode "Galaxy Brain," Death reveals her plan to kill God, related to his book in her library, which details how every being the universe will eventually die (We first learned about this library in Season 13). While the books aren't set in stone (Dean, in particular, has a whole shelf of different ways to die), "everyone has one," meaning that even in the multiverse of Supernatural, with all its gods and angels and demons, no one is truly immortal.
On the other hand, in Westworld, books don't depict the future, but rather the past. At the end of Season 2, Dolores accesses the lives of all the guests in the park, which were collected by Delos (the company that runs the park) in order to work on an immortality project. But, Dolores uses them instead to gain information on the outside world, which she soon intends to escape to. The lives are represented in the "user interface" as books, lining countless shelves, each filled with lines representing the information they contain. We've seen her make use of the information multiple times in Season 3--first to find a tech mogul she could blackmail for money and insider information, and then again to get as close as she can to Liam, the current head of Incite, the company that more-or-less runs the outside world.
In both series, books are a source of knowledge, and through that knowledge, power. Dolores uses knowledge of the past to carve out a life for herself in the outside world, and Death plans to use knowledge of the future to kill God. While almost certainly unintentional, it's an interesting duality. But more importantly, this use of books represents something about how we as a society see them. While the idea of a book that sums up someone's life isn't unheard of even in real life (Dolores even calls this out, referring to one of the books she read as "an unauthorized autobiography), they're usually written by or with the input of whoever the subject is. In contrast, a book that depicted the entirety of a person, not just the parts they decide to show, would be a violation, something that could be used as a weapon.
In addition, both shows make a point of choices. Dean's shelf of books all represent different ways he could die, and Death specifies that which one ends up being true depends on the choices he makes in life. In contrast, the books Dolores reads are a summation of past choices, of whether to be a white hat or black hat, not of choices that determine the outcome of one's life but of choices that determine who a person is. The focus on someone's individual personality makes sense, given Delos intended to use the books to perfect making perfect copies of someone, to make them "immortal."
But regardless of the similarities and differences, we've yet to see the last of the books in either show. Dolores read many more books than the two we've heard her mention, and Death only gave us a little teaser of what's in God's book, cryptically stating that Sam and Dean are "messengers of God's destruction." Supernatural is currently on hiatus due to a delay in production caused by COVID-19, but Westworld is still airing normally. Either way, we'll just have to wait to see what happens next, and maybe be a bit warier next time we visit our local library. After all, books have power.
Airing Mondays at 8 p.m. ET/PT on The CW, the final season of Supernatural stars Jensen Ackles, Jared Padalecki, Misha Collins and Alexander Calvert.
Airing Sundays at 9 p.m. ET/PT on HBO, Westworld stars returning cast members Evan Rachel Wood, Thandie Newton, Ed Harris, Jeffrey Wright, Tessa Thompson, Luke Hemsworth, Simon Quarterman and Rodrigo Santoro, joined by series newcomers Aaron Paul, Vincent Cassel, Lena Waithe, Scott Mescudi, Marshawn Lynch, John Gallagher Jr., Michael Ealy and Tommy Flanagan.