Someone may discover (or not discover) that he or she is a character in a number of narratives at the same time, some of them embedded in others. Or again, what seemed to be an intelligable narrative in which one was playing a part may be transformed wholly or partly into a story of unintelligable episodes.
In life, as both Aristotle and Engels noted, we are always under certain constraints. We enter upon a stage that we did not design and we find ourselves part of an action that was not of our making. Each of us being a main character in his own drama plays subordinate parts in the dramas of others, and each drama constrains the others. In my drama, perhaps, I am Hamlet or Iago or at least the swineherd who may yet become a prince, but to you I am only A Gentleman or at best Second Murderer, while you are my Polonius or my Gravedigger, but your own hero. Each of our drama exerts constraints on each other's, making the whole different from the parts, but still dramatic.
MacIntyre is writing against the liberal, atomistic understanding of identity for one that is contextual, contingent, and narrative. Which really makes much more sense than the abstract and independent individual.
(In Liberalism and its Critics, ed. Michael Sandel.)