In this dissertation, I explore the intersection between fraternity and governance within fifteenth-century English literature, arguing that the familial relationships in these texts go beyond the interpersonal and are used by the authors to think through questions of both self-governance and the governing of the polity. Drawing on methods used by historians of emotions, such as Barbara Rosenwein, I trace the usage of terms indicating brotherhood across a variety of genres (romances, plays, sermons, letters, and wills), and consider the depictions of brothers' behaviours, motivations, and speeches in these texts. This analysis reveals that governance and fraternity are linked in several unique but complementary manners in fifteenth-century England, and that authors utilize fraternal relationships to demonstrate a wide variety of good and bad governance of self and others. In each chapter, I trace the discourses of fraternity within a unique conceptual framework: Scriptural foundations, Classical foundations, the Rise of Arthur, the Fall of Arthur, and finally the Rise of the Gentry. The variety and prominence of discourses of fraternity within the genres and texts studied here demonstrate the power of brotherhood in the cultural imaginary of the period. The authors of these text all grapple with the double-edged sword of fraternity, exploring how characters navigate the complexities of brotherhood. The authors use fraternity as a tool to explore how interpersonal relationships can have a larger impact on the polity around them, proving that fraternity, much like authority, can be used and abused for personal gain, often to the detriment of others.