"We can't just do things on our own. This isn't a solo mission. I'll help you understand the true affiliation with your allies!"
—Freesia, teaching Marryl about partnership
The Protagonists refers to the entire storyline's 'good' characters who assists and relates themselves in making sure the storyline have an happy ending. Other Protagonists also refers to the characters which have affiliation with the main characters of the story.
Note that ALL PROTAGONISTS are recruitable in missions.