What is the Rot? Why is the Rot?
Spoiler Warning and Holy Wall of Text Batman Warning. I got WAY too into questioning the turbo-cancer here, hopefully my rambling makes sense.
So, the Rot is… weird, from a biological standpoint. Really weird, if you stop to think about it. It’s most frequently described as some variation of cancer, and it certainly fits the criteria for it. Caused by damage to DNA? Check. Multiplies uncontrollably? Check. Comes in both benign and malignant forms, one stationary and the other mobile? Big fat check. Heck, even the Rot cysts eating other creatures kind of fits, according to some research I’ve done – there are apparently cancer cells that will eat other cells, which makes sense in hindsight since cancer cells are cells that have lost important genetic restrictions, which may include whatever lets cells identify other cells as “do not eat.”
(I ain’t a biology whiz and I’m doing research on the fly while getting my thoughts out here, so take whatever I say about biology with a grain of salt)
So, Rot is clearly cancer of some kind, right? Case closed. Except when me and a friend of mine were talking Rain World theories on Discord, she brought up some interesting points that got me thinking.
First point: Rot cells obviously mutate in a way that affects FAR more than just cell replication and termination. Some of the cysts can HEAR. As far as I know, cells in the body do not hear sounds. They communicate via chemical signals and maybe, MAYBE react to temperature. Hearing involves complicated, specialized sensory apparatus to pick up on vibrations in the air. Even if you simplify it and say that it’s only vibrations, that’s STILL a multicellular thing, not a single-cell thing. It’s something that took millions of years to evolve on Earth, if not billions.
And while Rain World’s timeline goes on for long enough that it those kinds of mutations might happen eventually, Rot cysts have the ability to hear pretty much right from the start – because even the Proto-Long-Legs react to your presence like the Daddy Long Legs do, and the Rot in Spearmaster’s campaign, where Pebbles has recently contracted it, reacts the same way as it does in later campaigns. It’s already able to hear.
As far as I know, cancer just means the same cell duplicating over and over again. Are more mutations possible with each division, as errors are made in the DNA during splitting? Probably. But not to THAT extent. There’s no way a lump of cancer somehow mutated the exact complicated genetic blueprint needed to grow organs, at least not without outside interference.
Second point: Cases of Rot are way too consistent across the board. Now, we don’t have a huge sample size to work from, but from what we see from both Pebbles’ Rot, and Hunter Long Legs, they’re… pretty similar. Hunter Long Legs is basically a mobile Rot cyst. They move the same way, seem to grow the same way (starts as a growth inside/on the body before eventually freeing itself from whatever wall/flesh it grew from in some capacity and moving elsewhere), they have the same senses, and they even eat the same way, via something like phagocytosis (how white blood cells “eat” invading organisms via engulfing them and breaking them down in a sac in their main “body.”)
Now, this doesn’t tell us much, because cancer, when it does emerge, is pretty consistent in symptoms/what the mutated cells do once they start replicating. It’s pretty much the same regardless of whatever organism the cancer is happening in. But what ISN’T consistent is what causes the DNA error in the cancer cell in the first place. IRL, cancer can be caused by all kinds of things – smoking, radiation poisoning, being out in the sun too long, drinking deadly chemicals and whatnot, anything that damages DNA. But in RW, the only time we ever hear Rot talked about, or see it present, is in the context of an iterator having f*cked up while mucking around with DNA. Pebbles was trying to create an organism that could change his own genome, and No Significant Harassment created Hunter as a messenger and probably mucked something up in the process in his haste to get them to Moon.
This doesn’t mean that there aren’t other causes of it, of course, we’re working with a sample size of two in an apocalyptic world with who knows how much potentially DNA-damaging stuff around, but… that’s still awfully consistent.
So, combining these points and everything we know to be canon, Rot is:
an organism that lives inside another organism
Until a certain condition is met, it cannot harm said host organism.
Once said condition is met, it goes out of control, wreaking havoc on the organism’s systems and mutating, giving it sensory capabilities and an appetite
Said condition is apparently someone messing up when re-arranging genomes, in yourself or others
It is widespread across multiple different species, at least iterators and slugcats but potentially other species as well.
Once you have a bad case of it, it is apparently NOT CURABLE. Pebbles tried everything he could think of but apparently exhausted all of his options by the time of the Survivor/Monk campaigns.
So, with all the context FINALLY laid out, here’s my wild theory: Rot isn’t a cancer. It’s a symbiote turned parasite. Specifically, I believe it’s a symbiotic microbe that lives inside the cells that make up every other creature in Rain World, and is held in check by a specific gene that all species share, and altering or getting rid of that gene causes it to go berserk, taking over and eventually mutating the host cells.
Yeah, I did watch Parasite Eve let’s plays as a kid, why do you ask? Anyway, hear me out here.
There is precedence for single-celled organisms living inside of other single-celled organisms. They’re referred to as intracellular endosymbiots (hopefully I got the spelling right there), and the most well-known one is probably the mitochondria. The powerhouse of the cell is thought to be descended from some bacteria way, WAY back that was engulfed by a larger cell and not only survived it, but BENEFITED from it. Since then those ancient proto-mitochondria and eukaryotic cells have mutually evolved to be dependent on each other. So it’s entirely possible for something similar to have happened in Rain World.
However, I don’t think it happened NATURALLY, here. Because something that’s able to take over a cell entirely and begin wildly mutating it is NOT something your average cell wants inside of it. There’s a VERY high chance of extinction if you do that. Which means that of course those funky bio-tech loving Ancients either took a look at a wildly dangerous cellular parasite and went “hmmm we can use this” or made one themselves.
Why did they do this? Who knows! Currently, I’m tied between “they needed a better powerhouse for the cell to power the various weird adaptations they’re building into various creatures,” “there was some sort of disease that this parasite gave immunity against and they wanted to make use of it,” and “it gave their creations massively powerful regeneration factors that made them much easier to maintain.” Possibly it was all three. Whatever the reason, the Ancients either found or created this parasite, and put it into their creations’ cells, hoping to reap the benefits.
Well, they got the benefits, but they also got a microbe that hijacked the cells and harnessed their pre-existing DNA blueprints to build organisms disguised as great big blobs of cancer. Which is not exactly ideal, but hey, they just had to figure out a way of keeping the cell hijacking from happening! And the way they ended up going about it was to alter the thing so that so long as there was a specific DNA sequence in the cell, it laid mostly dormant. All the benefits, none of the risks – so long as that specific string of genes remained intact.
And then BECAUSE it was so beneficial, they spread their artificial symbiote and it’s genetic reins throughout ALL of their creations, from the smallest pipe-cleaning slugs to the iterators. Which meant that as their purposed organisms replaced most of the original ecosystem, they spread the symbiote as well. Thus making it possible for pretty much ANY creature on the planet to come down with a bad case of the Rot. And with the iterators, I wouldn’t be surprised if this symbiote is tied to their self-destruction taboos. Try to cross yourself out? Well, it’s gonna maybe happen now, but it’ll be a slow painful death as you’re eaten alive from the inside and all your own parts turn against you, so was it really worth it?
And they never told their creations this perhaps even actively hid it, because why tell them the cause of the main deterrent to them mucking with their taboos? They might find a way around it. The iterators were left ignorant of how Rot works, and because of this they never figured out that Rot HAD a cure after all: rebuilding that genome that reins in the symbiote. Because why in the name of the Void would they repeat the same mistakes that gave them Rot in the first place, and potentially make it worse?
