They Both Die at the End is a young-adult novel about a society in which technology can determine and report the days on which individuals will die. In a general sense, the ability to predict death is surrounded by economic and cultural elements. An industry of death, including social media, apps, theme parks and other businesses is indicative of how callous attitudes toward life can be. Everything can be packaged and sold, even human mortality. Additionally, the lives of Deckers—people on deck to die—are regarded in various ways that reveal a spectrum of perspectives. The Death-Cast employee Andrea, for example, dehumanizes those she calls, believing those who get the alert are essentially already dead and no longer real people anymore. By contrast, Dalma is the creator of Last Friend, an app that connects people so that Deckers can have someone to spend their End Day with. 

The novel is told in chapters that are either from the two protagonists’ point of view or from the perspective of minor characters who are somehow connected to Mateo and Rufus. This perspective emphasizes the motif of interconnected lives. Each chapter indicates if the point of view character is dying or not and a time stamp that counts down the boys’ End Day by the minute, creating a rising tension as the day wanes and, inevitably, the boys’ time runs out. As they progress through their End Day, Rufus and Mateo each have encounters both intentional and serendipitous that lead them to emotional growth that results in the ability to love and be loved. In the beginning of the novel, both boys struggle with their identities and the way they’re living their lives. Both of them are on their own since Mateo’s mother is dead and his father is in a coma, while Rufus is a foster kid whose family died months earlier. Finding each other through the Last Friend app is indicative of their loneliness and desire to connect with someone else in a meaningful way before they die.  

Mateo’s isolation and anxiety keep him from interacting with the world and having the kinds of experiences he desperately wants. Instead of making friends and having fun, he spends his time playing video games and reading the blogs of people experiencing their End Days. Those passive and virtual experiences serve as a way for Mateo to avoid real and authentic experiences and relationships and insulate him from the world he avoids. Rufus, by contrast, is motivated by the anger and guilt that comes from surviving the accident that killed his parents and sister. He’s impulsive and hot-headed, actually receiving his Death-Cast alert while he’s savagely beating his ex-girlfriend’s current boyfriend. They serve as foils in temperament and personality, but they are similar in their search for a way to have meaningful experiences on their End Day amidst their own loneliness and isolation from others. 

As Rufus and Mateo make their way through the hours they have left, various experiences result in emotional growth. With death imminent with every passing moment, every second becomes precious for the boys, and they weigh their actions carefully. A trip to Make-a-Moment serves as a reminder to them both that living authentically involves risks both emotional and physical. The stakes rise with each second as they both reflect on how they should have been living more intentionally all along. Mateo regrets not taking more risks and developing relationships with others while Rufus ignores the unresolved pain and guilt he carries that makes him hardened and callous. Mateo transforms from a quiet, shy, anxious person to someone who can not only admit to himself who he really is but reveal it to Rufus. Similarly, Rufus processes the death of his family and releases the anger it’s left in him. As Rufus encourages Mateo to take chances and be himself, Mateo helps Rufus be more thoughtful and intentional. Through their growing relationship with each other, they not only learn to how live the lives they’ve always wanted, but how to give and receive love. 

When Mateo and Rufus spend time at Clint’s Graveyard with their chosen friend-families, they demonstrate how they have learned the importance of meaningful relationships. Mateo and Lidia get to say goodbye, and Rufus likewise gets closure with Aimee, Malcolm, and Tagoe. Mateo and Rufus’s evolution is complete in the climactic moment when the boys express their love for one another. At that point, they have learned that although death is a part of life and loss is a part of love, what they found is worth the pain. Their deaths are inevitable but victorious as their lives end with love and joy. They have become the people they’ve always longed to be and left behind a legacy of memories for others to remember them by.