Ask any fighter; experience trumps strength, but experience and strength trumps all. This may seem like a strange way to start a piece about writing stories, but as per usual I will do my best to bring it home.
Spoiler(ish) warning for The Last of Us and the Fallout series.
Monsters, mutants, aliens or whatever horrific enemies your protagonists will carve their way through as your story progresses, individually they tend to be pretty static in their abilities. You may get different varieties of said enemies, but typically they’re separate from one another while also working together. You can have the physically weak but fast and numerous ones, they’re good cannon fodder for your characters to mow down. You can have the run of the mill grunts or drones, they’re basically comparable in ability to your protagonists and often make great opponents for them. Finally, there’s the big guys, the lumbering giants that tend to increase the likelihood of character death the second they step on scene. Each of these enemy types has its own strengths and weaknesses, and you can use them to your advantage when trying to tell a compelling story. One type on their own is a predictable affair, two different types requires some thinking and encountering all three becomes a tactical nightmare.
The key issue here is that while they’re typically united in a cause, doing whatever your characters don’t want them to do, these forces are typically comprised of disparate creatures. It’s the Vampire Lord’s undead horde, the Space Pontiff’s interstellar legion or the Orc King’s goblinoid swarm, it’s different creatures working together. If gives your antagonists some variety and keeps things interesting for the audience. This isn’t always the only way to create an antagonistic force, however.
Sometimes, enemies will start as the small and weak creature, then as time progresses they will morph into the typical grunt and then after a long while they will eventually transform into the lumbering brute. It’s a great way to show that the force your characters are facing is a truly homogeneous group, despite their appearances suggesting otherwise. Instead of being a menagerie of strange and horrific creatures that are working together for some random reason, they’re all the same and working together for that exact reason.
While having a unified force, comprised of different sub-categories of creatures that evolve into one another over time, does come with its narrative advantages, it also creates a serious problem. If time is the only deciding factor, then it’s inevitable that your characters are eventually going to have a literally big fucking problem on their hands. To showcase this point, we’re going to be looking at two series - The Last of Us and Fallout.
In The Last of Us, humanity basically gets wiped out by fungal zombies. When a person becomes infected, they start out as a Runner, then after about a month they become a Stalker. After about a year of being a Stalker, they become a Clicker. Then, roughly ten to fifteen years after infection they become a monstrous Bloater. Their abilities change somewhat as they evolve, becoming less human as they change, but the basic idea is that they become more difficult to deal with the longer they’re infected.
In the Fallout series, most notably Fallout 3, Fallout 4 and Fallout 76, East Coast Super Mutants continue to grow as they age. The FEV mutagen that turned them into Super Mutants continues to change their physiology and while they’re already stupid brutes, eventually it turns them into lumbering Behemoths that are of gargantuan proportions. This worked in Fallout 3 and Fallout 4, because they’re set over two centuries after the world ended and Super Mutants were being created for roughly that length of time - two centuries to turn into a Behemoth isn’t that big of a deal. Fallout 76 changed this, however, because it’s set only 25 years after the nuclear apocalypse and there are Behemoths running around. This latest addition of the Fallout series puts the issue into roughly the same time frame as The Last of Us.
Whether you’re a survivor in The Last of Us or Fallout, you’re logically screwed just by the way in which the creators have crafted the world. Ten to twenty years is all it takes for base enemies to turn into the strongest enemies that’re available, and they don’t even get a say in the matter because it’s a natural process. Every human who is infected in The Last of Us will turn into a Bloater if they survive long enough. In Fallout, every human that’s dipped into FEV will turn into a Behemoth if they survive for long enough. It’s literally only a matter of time in both cases. Since the narratives need these creatures to be the biggest threats in their respective stories, the logical progression of events is that humanities chances of survival continue to plummet the longer the timeline continues. The Last of Us is set 20 years after the world ended, while most of the Fallout series is set centuries after the fact, which is plenty of time in both instances for the vast majority of these creatures to reach their final form.
The thing is, this could actually make your world that much more interesting. Instead of ignoring the rules you write into your own world, you can run with them and create a truly deadly setting that is a serious threat to your characters. In both The Last of Us and Fallout, if things had progressed as they should have, with humanity hiding from their growing problems instead of dealing with them… well, now they’ve got a problem that’s a million times worse. If time is the deciding factor in your enemies strength, then time is the enemy. If simply not dying is all it takes for your enemies to reach ultimate monstrous god mode, something even your protagonist and background characters have managed, then use that to your advantage.
If your zombies or mutants evolve over time, use that to create a story with unique zombies or mutants. If you don’t want your world overrun with final form enemies, then don’t set the story in a time period where that’s the logical conclusion. You’ve still got all the years before that to play with, so go nuts in the safer years. If you want an enemy force that is linked (wherein each creature evolves through each of the different forms) but you don’t want a world that’s inevitably overrun by final forms, then simply don’t make time the deciding factor. Have them get injected with a serum, or have it as some innate biological process that’s triggered when the need arises. However you do it, the golden rule is to keep your world consistent. The less your readers/players/watchers have to question how things work, the deeper they can invest in your world without making excuses for it.
This post isn’t about ripping on The Last of Us or the Fallout series, they’re games which means they’ve got more than just narrative issues to contend with. There’re gameplay balance issues as well, which are just as important. The thing is that a simple tweak of the narrative would allow everything to line up perfectly, and then there wouldn’t even be any issues for me to write about. If you’re making a setting, for a book, movie or game, think a little further down the line about where the natural progression of the events you set in motion will logically take things. Who knows, things could actually end up better than you originally expected?