The SEP article on mathematical style got me thinking: what is the relationship between mathematical style, mathematical fictionalism, and ethical style/fictionalism? There seem to be at least three options: the ethical hyperstory is better expressed in broadly mathematical, not dramatic, style, or vice versa, or the hyperstory is equally well-expressed in both writing styles.
If one is tempted by the possibility of using the "according to the story of X" operator in fictionalism as a logical operator simpliciter, one could develop a clever example of the mathematically-styled ethical hyperstory, I suspect. Could you, perhaps anachronistically, interpret Plato in these terms? What was Plato's apparent opinion of dramatic storytellers, if anything? Or is this a shadow or reflection of what Rawls was prophesying of when he spoke of moral geometry?
EDIT: one way I could see this playing out would be to say that invoking formulaic vs. purely quantitative alternations of ordinal judgment is as such modulo the axioms of reduced comprehension and extensionality, respectively. In other words, the axioms of ZFC comprise the ZFC hyperstory proper. Then let the initial story operator in fact just be the zero-interval of an entire operator scheme, so that you automatically end up with arbitrarily many such operators and counterpart hyperstories. For starters, this implies that the deontic hyperstory pretty much certainly exists in the sense that the erotetic component of the narrative structure is given to us in the form of legitimate questions. Forget whether, "Murder is wrong," is objectively or absolutely factual. At least for a second. Because you can substitute a more precise question for the mystery of those standard descriptions, viz. whether the pure question, "Is murder wrong?" is indeed plainly enough given as a real mystery that we should be able to solve? So anyway, since out of the infinitely many hyperstories there are, at least one is probably the actual deontic one, then...
But moreover, with these neverending stories, you'd have a mathematical realm for the deontic hyperstory anyway.
Other "models": a category of hyperstories, with narrative mappings; Alessio Moretti's geometrical logic (you would take his deontic infinite-dimensional fractal and have this supply an infinitary logic of whatever appropriate magnitude with conjuncts and disjuncts exhaustive enough to map out a universe-sized set of facts). (Indeed, this whole evaluative process can be motivated, in part, by consideration of infinitary logic in general.)