This paper seeks to challenge the notion that European Christianity was untouched by Asian religious influence during much of the Common Era. Rather, I propose that certain Indian ethical tenets were incorporated into Christian ascetic practices as a consequence of interaction with heretical intermediaries. In medieval Europe, the spiritual kinship of animals and humans was widely taken for granted by common folk and heretical clerics. Indic religious doctrines on this subject may have diffused gradually into Western popular religion even while the Church worked systematically through official channels to prevent their transmission. Inspired by the work of Graeme MacQueen, I examine evidence of saint–animal interactions in several medieval hagiographies. These saints’ lives model ethical responsibility toward nonhuman life. I argue that Buddhist Jataka stories provide the prototype for these characters. Ultimately, similar ethical tenets were integrated into orthodox Christian asceticism by Saint Francis of Assisi. Some of Francis’s inspiration may have originated in Asia, later carried to Europe along the Silk Road as doctrines of the Manichees: secretive, syncretistic heretics continuously persecuted by the Church over the better part of a millennium.