My story has a protagonist, well several in fact, but they're not constant. But a friend said that he didn't have a constant protagonist and his book failed to get published, so I'm worrying that mine won't work. The story doesn't call for someone who torments the MCs for the entire book, probably a few chapters at max, but it has several threats in several groups of bandits, cannibals and human/plant hybrids. So will this effect my chances on publication? By the way, my friends book was great, well written and a top class plot.
Your friend's book failed to get published because his/her's agent or publisher thought the book didn't meet some criteria standard. I don't know, maybe the professional folks he went after wanted basic constant protagonist kind of storyline. But this is what I don't know. Is your protagonist constant through-out the book? Does he exist from start to finish? What it sounds like to me that your MC is going on an adventure and runs into antagonizing entities that aren't exactly a main character that would be the antagonist. If so, that story could work out. It's really in the publisher's interest. Any kind of storytelling works in my opinion.
What people want to see in a story is the hero vanquishing or overcoming something. If there's no constant flesh and blood antagonist which the hero beats at the end, why not make one of his traits become his enemy instead? The "smaller" enemies would then become a trial of sorts. Is he lacking courage? Is he trying to overcome his fear of monsters? Is he running against the clock? Just my 2 cents
Are we here talking about "constant protagonist" or "constant antagonist"? Your title and your post seem to say different things. I have completely different answers for each.
In that case I don't see any harm. Putting it in very basic terms, antagonist are just hurdles or part of hurdles the antagonist has to cross to reach its goal. If the story revolves around overcoming this one antagonists then yes you need a constant, well developed antagonist. But if somebody is saying this is the broad criteria for an antagonist so that the novel be considered for publishing then I think that's wrong. When the protagonist changed it might also changed the goal of the protag which means there might be changes in the hurdles (including antags) too. Antags are the supporting roles, supporting the character arc of the protag. Therefore how an antagonist is developed should entirely depend on the character development of the protagonist and the plot.
In Finland we have a concept called the red thread, something that leads you from start to finish. In many literary instances, it's the plot, the reason why the hero takes up his quest. It's not unusual at all to have several antagonists (not related to one another in any way) along the way, that's not a problem. What sometimes helps is to have some final hurdle the hero has to overcome before he attains his goal, but it doesn't necessarily have to be evil incarnate. In one story I've written with KaTrian, there is no great final boss like at the end of many video games. Instead, there is a specific reason (unrelated to the antagonists) why the characters embark on their journey, and the antagonists they encounter are just obstacles on their way as they move towards their goal. So far we haven't seen that as a problem as we've managed to tie the conflicts to the red thread in one way or another despite a few "side quests."
