With regard to a theory of transtextual characters, central questions remain open or have hardly been identified as a problem. The article discusses some of these questions from a medievalist’s perspective, such as what the basic category of a literary character to be understood as transtextual is: ›text‹ (which would lead to the term ›transtextual‹), a piece of work including a specific ›storyworld‹ (which would lead to the term ›transdiegetic‹), or only a fictional storyworld (which would lead to the term ›transfictional‹). As a prerequisite for this discussion, I try to clarify how the identity of a character in different ›storyworlds‹ can be defined (e.g., via a prototype model or universalist theory). Although this has already been discussed at length, the relationship between the concept of ›storyworld‹ and literary theoretical concepts such as text, manuscript, work, and variants is still missing. The same is true for the connection between the theory of transtextuality and philological concepts that describe the relationships and interdependencies between texts, works, versions, redactions, and adaptations. Historising the theory of transtextuality therefore first requires a clarification of the concept of ›work‹, or the criteria for conceptual identity of a piece of work. Another unresolved fundamental question is whether transtextuality presupposes fictionality. This question has hardly been asked so far because transtextuality has almost exclusively been discussed using examples of fictional characters from modern literature (such as Sherlock Holmes or James Bond) or from entertainment media (such as Tarzan or Lara Croft). In this paper, I discuss this question for Middle High German narrative literature. As an example for non-fictional narratives, I have chosen biblical narratives (›Bibelepik‹), i.e., narratives that use either biblical or apocryphal material as their source. Among other questions, the article discusses the issue of the extent to which the specific conditions of authority and validity of sacred texts limit their potential for variation. This is because the licenses for shaping and re-accentuating biblical figures are extremely limited: spiritual storytelling is about retelling the events revealed by the Bible (and apocryphal biblical narratives) over and over again, but without changing the main plot or adding new characters. The main argument against extending the concept of transtextuality to characters such as Adam, John the Baptist or Herod, however, is that factual narratives do not produce their ›storyworld‹ themselves as fictional texts do. Their storyworld is to be understood as the actual world. The transgression necessary for a character to be transtextual, transdiegetic or transfictional can only take place from a distinguishable storyworld, and that is a fictional one.