The definitive biography of Dietrich Bonhoeffer, published in 1967, was penned by his friend Eberhard Bethge. The biography follows a tripartite narrative of Bonhoeffer's life as theologian, Christian, and contemporary, a division that became blueprint for future Bonhoeffer biographies and has remained uniquely influential even to this day. Research on Bethge has therefore become an independent research concentration in the wider field of research on Bonhoeffer. This article uncovers the internal connections between the dynamic development of Bonhoeffer's personality as portrayed by Bethge and the stages of the growth of a protagonist in a Bildungsroman, a parallel neglected by other researchers. In doing so, the present study aims to explain why Bethge's portrayal of Bonhoeffer has outlasted all the others.