The primary theme explored through History Is All You Left Me is grief and moving on. The primary vessel for this theme is Griffin Jennings, as he deals with the aftermath of Theo’s death, but it’s present in the details of every character who cared for Theo McIntire. Jackson Wright and Wade Church struggle with Theo’s death. Theo’s dad begins smoking again, Theo’s mom stops dying her hair, and Theo’s sister, Denise, doesn’t care to help with the baking on Thanksgiving. All these characters in the periphery fight their own battles against grief while Griffin fights his in the main narrative.

In the early “Today” chapters, Griffin finds every step from his bed to Theo’s funeral unbearable. The only reason Griffin goes at all is because “there’s a clock on this thing. The service is today. The burial is tomorrow. I don’t know what comes after that” (19). Griffin’s struggle to look beyond Theo’s burial shows how thick the cloud of grief around him is. He’s so lost in his emotions that he cannot process that life will continue once Theo is buried. This moment shows how grief can make it difficult for one to look to the future.