This paper argues that the unknown editor of Ad M. Caesarem et inuicem arranged the letters in their non-chronological order so as to create a work that is essentially historical fiction, providing the reader with a romanticized version of the early life of Marcus Aurelius, a Marcopaedia of sorts or even a quasi-prequel to the Meditations. The paper demonstrates that the anomalous Book 5—full of shorter, less elaborate letters—can be read not only as an appendix composed of leftover letters but also as a part of the broader narrative. Book 5 creates a sense of closure to the epistolary fiction created by the editor. In particular, this article focusses on the recurrent motif of Fronto’s health; the frequent references to Fronto’s illness work in a metaliterary fashion to signal the impending conclusion of the work, creating a sense of resolution for the health/sickness letters appearing in Books 1–4. The sickness/health topic also connects to certain philosophical topoi regarding death, illness and consolation—a connection that is appropriate in light of the young Marcus’ burgeoning interest in philosophy.