Several characters in nonfiction?

ENS

Think of the plural form of a letter that often appears in printer settings.

The clue plays on the word "characters" to mean both fictional people and letters. "Several characters" hints at multiple letters, specifically the plural of "N," which is "ENS." In nonfiction, "ENS" could also humorously suggest "essays" or "articles," but the main trick is the double meaning of "characters." The answer is simply the letters E-N-S.