There are Three Essential Characters in Every Story. There may be any number of side characters, but in traditional Adventures, and Romances of every stripe the main conflict is usually, if not always, a triangle of complimentary opposites.
Translation: You could tell the WHOLE story with ONLY these Three Characters; perhaps not with any real detail, but you could still do the entire basic plotline. (Yes I know, I’ve said some of this before. Bear with me.)
Yep. I’m sure you’re familiar with: Hero – Villain – Heroine (or Sidekick) already. Those are pretty darn standard. So, let’s define them in a more Literary, (and complicated,) fashion shall we?