In critical dialogue with contemporary ‘narrative medicine’, a concept popularised by Rita Charon, this article re-examines representations of mental illness in the short prose of the German Expressionist writers and doctors Alfred Döblin (1878–1957) and Gottfried Benn (1886–1956). Taking as my focus Döblin’s story, ‘The Murder of a Buttercup’ [‘Die Ermordung einer Butterblume’] (1912), and Benn’s cycle of ‘Rönne novellas’ (1916), I argue that their protagonists embody a form of ‘narrative modality’: a futile attempt to fashion entangled and chaotic mind-body relationships into self-controlled and socially sanctioned subjectivities. Michael Fischer’s hallucinations have often been read as the symptom of nature’s mythic revenge on the alienated modern subject, and they have also been associated with various specific psychopathologies. By considering the story’s resonances with contemporary biopolitical discourses, Döblin’s own psychiatric research, and Oliver Sacks’ neurological case studies, I read our inability to ‘pin Fischer down’ both as the mirror image of his inability to control a wayward body and mind, and as the marker of his broken yet irreducible humanness. Benn’s autobiographically inflected ‘novellas'—as he termed his experimental pieces—trace the repeated collapse of Dr Werff Rönne’s attempts to re-establish a stable sense of self. This collapse sounds the death knell for those endeavours and, at the same time, it opens radically new possibilities for both thinking and being. My article shows how these authors probe the very limits of literary narrative in its capacity for doing justice to the strange and singular lived experiences of mental illness.