This dissertation examines how medieval heroic literature exploits the interpretive ambiguity of emotions to interrogate ethical mores. Reading heroic texts from English, Irish, and Scandinavian literary traditions as figurations of a historical imaginary, this dissertation focuses on "negative" affects like anger and fear to examine how feelings illuminate a dialectic between nostalgia for a constructed past and concern about a dreaded future. I assert that, across the medieval North Atlantic, heroic poetry reveals a critically-unacknowledged concern with the ways affective connections create social cohesion, yet lead to almost inevitable destruction. Emotions elucidate a liminal space between the embodied and the psychological—they are felt in both senses of the word. They also maintain tension between past events and potential futures, and indeed, between the heroic past of a text and the diminished present occupied by its reader. This project reassesses modern assumptions about medieval feelings and posits a new medieval-heroic theory of affect. These feelings, I argue, create an atemporal hermeneutic, a way of "thinking about feeling," through which I reassess how literature can display concerns about the ethical choices available in past, present, and future. This project offers a new and trans-historical way to read ethics through emotion—moreover, it demonstrates how medieval literature speaks urgently about ethics to non-medieval audiences, from early modern authors to contemporary readers.The dissertation is divided into four main chapters. In the first chapter, I demonstrate how laments transmute solitary grief into a future-oriented community affect while allowing mourners to question the political causes of grief. In the second chapter, I argue that while anger breaks relationships through violence and feud, as is often discussed in the context of Old English literature, it also creates relationships that are bound to fail. The third chapter takes account of how shame operates at two conflicting but mutually constitutive levels: that shame is used to critique the power structures that inculcate it while at the same time seeking to control "non-heroic" activity. The fourth and final chapter examines how the spatiality of fear functions alongside processes of thinking and knowing, bringing the mind in proximity with possible futures; by linking the emotional to the embodied, readers engage affectively with the often-fantastical traumas experienced in heroic literature.