This is a suggestion by Ryuu_Night! Pretty cool idea buddy, had a bunch of fun :D

(Tbh this AU is probably the closest thing I'll ever do to being a crackshot, cuz even I have almost no clue what I'm doing here XD. Like, I had a lot of fun making this, but I'm worried it's bad.)

So in this AU, Sabre is a creature of Darkness... but a very different kind.

Long before the events of the time of the Third Hero started, in a place entirely corrupted at the bottom of a jungle cliff, Nightmare Steve is overlooking creation of new Darkness creatures for his army. They come out of concentrated Darkness gatherings that are on the walls and floor, and each new creature mindlessly shuffles into the array of ebony figures after they pop out of the abyssal goop.

Nightmare is about to order to halt production as the amount of new recruits is soon going to reach the quota, but when he turns around he quickly hears a strange sound, kind of like something really squishy like a rotten fruit or something hit the ground and splatted. Turning back around and looking at the spot of the cliff that's covered in Darkness, he sees a strange sight even he's confused by.

There on the dirt is a gooey mess that very faintly resembles a person, but seems to be some kind of Darkness creature... maybe. It's body is entirely black and kind of melt-y, bits of liquidy Darkness dripping from it like slime. However, it's different from a normal Darkness creature; It has a dark grey shirt and the goo-like Darkness on top of its head is kind shaped a little like hair, even having a deep brown color. It also seems to have shorts that match its grey shirt, but are halfway covered in malformed Darkness, and the thing barely even has legs, what looks like is supposed to be legs both melted and stick together.

It has other unusual features that would be considered lucky for a Darkness creature to have, but they're all deformed. It has visible eyes, but neither of them can focus. It seems to have actual hands rather than pointed claws, but they have the same melted look as the legs. It has a mouth, but all that comes out is an assortment of pathetic squeaks and strange noises. It has actual pupils in its unfocused eyes, which either signifies that it should be more powerful and have a better infection radius or that it's sentient, but the ground below it doesn't change at all and seems to stay normal, and it very much doesn't seem to be all that smart. All this, and not to mention that it's even smaller than the other Darkness.

The weird Darkness keeps trying to get up and use its basically nonexistent legs, but all it does is weakly flop around on the ground and occasionally flop itself on its back or on its stomach again using its arms. A normal Darkness creature that also just emerged walks over and picks up the deformed one by the back of its shirt, holding it up in the air. The deformed Darkness turns its head in the direction of the normal Darkness, and Nightmare expects the thing to at least try and fight, but all it does is:

"...What on earth is wrong with this one?" Nightmare thinks as he walks over.

Nightmare takes the deformed creature from the Darkness and sends it away. The deformed creature looks confusedly at Nightmare as it tries to make its eyes focus, but keeps failing. Nightmare walks over to one of the Darkness creatures that he's been commanding for a while and hands the strange, disfigured new Darkness to it.

"Get rid of it, I don't care how just- Get this thing out of my sight." Nightmare tells the Darkness as it also looks confusedly at the creature. "It'll obviously be no use to us; It's extremely malformed, and I can tell it's not even connected to the hive mind. It'll probably die within a few days anyway."

Nightmare then walks off, and not knowing really what to do, the Darkness creature throws the malformed creature on the floor. Now even more confused, and even a little scared, the strange Darkness looks up at the normal one only to see lightning strike down upon it as the normal Darkness teleports it away.

Little did Nightmare know how much of a problem that little thing would be in the future.

A week passes, and the deformed creature has gotten used to living in the forest it was teleported to. It doesn't really do much, mostly wanders around with its newly formed legs that it made from the stumps of dark goo it had after a lot of trying... although it still doesn't really know how to walk, and its lack of focus doesn't help. It falls over every two or three steps.

The creature can't even infect anything, so it's extremely defenseless. It couldn't harm a bird, much less any other animal. However, everything leaves it alone, and it doesn't know why. As the days passed, a word kept echoing in its mind: 'Sabre'. It begins to think it's a name, his name in fact. It has no idea that this isn't normal, that he isn't normal.

One day, he hears a commotion from a place outside the forest. Curiously (and without any sense of self-preservation), he approaches the end of the forest and looks out past the trees, wobbly leaning against one to keep himself from falling.

There, Sabre sees some familiar-looking figures chasing a few orange things into a place with a lot of buildings. He doesn't know whether it's the same ones he kind of saw in the cliff, or different ones.

However, for some reason it feels unreasonably mad that the dark figures are going after the orange people.

The deformed Darkness quickly drags himself towards the scene, losing balance and falling just as he reaches the other Darkness. Crawling along the ground towards the other creatures, he makes strange, angry-sounding noises, and even sounds as if he's yelling. Confused and actually kind of scared at the weird angry thing crawling towards them, the Darkness hurriedly runs away. As it runs off, the deformed creature continues to make angry noises at them, even when they're out of sight. He just keep going and occasionally waves a hand in the air.

Inside the village, the Orange Steves are extremely confused. A lot of them are gathered near the entrance of the village, watching the strange creature as it continues to yell and make noises, while the rest hide behind trees in the village or in their homes.

The Leader, wondering what all the loud chatter is about, exits his house to see his people just staring at the weird creature.

"What on EARTH is that thing?" The Leader wonders aloud, walking over.

"I dunno, it just showed up and chased away a bunch of Darkness that was chasing a few of us." An Orange Steve answers, holding a stick as if he's about to swing it. This particular Orange Steve has a mark that looks like a diamond shape on his face, and a few odd scars on his limbs.

"Actually... I think that thing is also Darkness." An Orange Steve wearing glasses and holding a book says. "I mean- look at it."

"I guess you're right..." Another Orange Steve says. This one has a flower in his hair.

"Then why'd it chase away the other Darkness then?" An Orange Steve asks, who has a flower matching the other one in his hair, and is carrying a small joke book.

"Well, there's clearly something wrong with it." An Orange Steve with a pickaxe says. "Maybe it has its mind messed up and confused the other Darkness for enemies?"

"Leader, do you know what's wrong with it?" The Orange Steve with the glasses asks.

"I don't have the slightest idea, bud..." The Leader says, staring at the weird creature.

"Hey, wait a minute." The Orange Steve with the scars holding a stick says. "If it thought the other Darkness was enemies, will it be nice to us?"

Before the Leader can say anything, another Orange Steve burst through the crowd also holding a stick, and starts walking over to the creature.

"I'LL TEST THAT!" The Orange Steve yells, already halfway to the creature. His yelling gets the deformed Darkness' attention as it looks towards the crowd.

"Loud, don't do something stupid!" The Leader yells after the Orange Steve.

Loud Orange Steve walks over to the creature, pointing his stick at him when he's right in front of it. The deformed Darkness looks at the Orange Steve with a blank expression... probably because he can't focus his eyes enough to see him properly.

"S-So? Is i-it friendly?" An Orange Steve in the crowd asks, sounding shyer than everyone else.

"WELL IT HASN'T ATTACKED ME, SO I THINK SO." Loud yells. "ALSO, THIS THING IS CROSS-EYED LIKE YOU WOULDN'T BELIEVE."

Sabre crawls a little closer to Loud, which make him panic. Loud swings his stick down at the creature, hitting it square on the top of his head. The crowd gasps, scared for Loud, but the creature just shakes his head for a minute and looks back up at Loud. Loud looks down at the creature, noticing it's not attacking him, and notices something else.

"UH- NEVERMIND THAT LAST BIT, I THINK I JUST FIXED ITS EYES." Loud yells at the crowd.

All of the village looks a little closer, and sure enough, the deformed creature's eyes are completely focused, looking at all of them.

The Orange Steve with the scars walks over to the creature as well, a few others following behind him. Orange Steve kneels down to get a better look.

"So... now what?" Funny asks.

"I dunno... I guess it is friendly." Orange says, tilting his head as he looks at the deformed Darkness. Sabre copies him, which makes him giggle.

"Um, it's really deformed... is it in pain?" Nerdy wonders. "Do we uh- kill it?"

Sabre hears that, and forgetting how to get up, rolls away in the grass a few feet away from the Orange Steves.

"...Looks like he can understand us." The Leader says.

Orange Steve holds out his hand towards the creature.

"Hey, it's okay! He didn't mean that!" Orange says. "You can come back over here, it's alright."

Sabre thinks for a moment, then rolls back to the group. Orange still holds him arm out, not sure what to do. Suddenly, the deformed creature smiles and puts his head against Orange's hand.

"AA-" Everyone starts to scream, but Orange stops them.

"Wait, look. He's not infecting me." Orange says, then he looks at where the creature has been sitting for the past few minutes. "In fact... he hasn't been infecting anything at all..."

Silence from everyone as they try to figure out what's going on with this creature. Then, a voice breaks the silence.

"Yo, does this Darkness not know how to Darkness?" Chill Orange Steve calls out.

"Y'know, I honestly don't think he does." The Leader says.

"We should take this to Red, he might know something." Orange says.

"Yeah, lets." Funny says.

It takes a while, given Sabre doesn't really get the concept of standing all that well, but eventually they get him balanced enough to where it's safe to teleport with him.

Red hears a knock at his door just as he was walks into his living room from his bedroom.

"Red? You home?" He hears a familiar voice say. 

"Orange? What happened?" Red asks. "Did some of your scars deform again?"

"No, uh... We found something... weird." Orange says.

"How weird, Orange?" Red sighs, walking over to the door. "I swear, if you just brought over another misshapen stick..."

"Like, weirder-than-me weird." Orange answers through the door. "Seriously weird. Just- open the door, dude."

Red opens the door, and doesn't know how to process the scene in front of him.

Orange Steve is holding up a strange gooey dark creature like a kid would hold up a cat. The Orange Leader, Shy, Funny, and Happy are behind him.

"What... on earth... is that." Red says, pointing at Sabre.

"We don't know, we were hoping you did." The Leader says.

"We're pretty sure it's a Darkness that doesn't know how to Darkness." Funny adds.

"A what- Screw it, let me see." Red says, reaching for the deformed creature.

Orange hands it to him, and Red studies the creature for a bit. Noticing his melted-looking state, odd features, and general inability to do things, Red knows that this thing is definitely extremely deformed... and it reminds him of when he first met Orange Steve.

"Well, he doesn't seem to be in any pain." Red says, noticing Sabre almost doesn't react to any poking or Red moving his limbs around, just looking at him and occasionally glancing at what he's doing. "Actually, he probably doesn't have nerves, to be honest..."

"Well, what do we do?" Orange asks. "He's friendly, he even saved us from other Darkness! I don't think we should just leave him like this..."

"He... saved you?" Red questions. "From other Darkness?"

"Y-Yeah, even though h-he was just on the ground, he s-scared them o-off..." Shy says.

Red looks at Sabre, puzzled. Sabre just bleps.

"...Hm. Well, then leaving him like this wouldn't really be fair." Red says.

"Hang on, I have an idea!" Orange Steve says. "Set him down for a sec."

Red places Sabre down on the grass, and Orange Steve walks up to him.

"Okay buddy, hold still." Orange says, then places his hand on top of Sabre's head, saying "Bap!" as he does.

Lightning strikes down on Sabre, which makes everyone jump. Once it ends, it seems like Orange's idea worked; Sabre is no longer melted-looking all that much, just a few spots. His hands and legs are more formed, looking normal almost. Sabre then tries to get up, and actually succeeds this time.

"Orange, what did you do?" The Leader asks.

"Uh- You know that little power I use all the time to fix broken stuff?" Orange says.

"You didn't." Red sighs.

"Well, it only took me using it on a larger scale, and it worked! Not like you can do something about it!" Orange exclaims, throwing his hands in the air.

That makes the other Orange Steve laugh, as Sabre smiles and looks confused. Red eventually laughs a little too.

From that point on, Sabre would stay with Orange Steve. Orange would help him learn things, like talking and reading/writing, with Red's help (speaking of Red, he lives much past his normal death date in this AU, helping Orange and Sabre with Sabre's turn from just Darkness to person). Now, it's not like Sabre is dumb in any way, it's like he learns things with a normal adult mindset and just uses what he learns like a little kid until he gets used to it (it's hilarious when Loud accidentally teaches him a few ✨words✨).

Now, about Orange/Rainbow here: In this AU, when he popped from the Orange Crystal, he was also extremely deformed like Sabre. Red Steve had been a friend of the village for a long time, so the Orange Leader immediately took him to Red for help. Red knew what to do and used a combination of his powers and medical knowledge to give Orange a normal look; the only remaining thing about the deformities was the scars. In Orange/Rainbow's words when he encourages Sabre not to be sad about being different: "Hey, you're not the only one like this, I'm deformed too! We're both weirdos and there's nothing wrong with it!"

As for Sabre, throughout the story, he slowly starts becoming more like a person. Instead of just Darkness, he turns into the person we all know. I made an order for this stuff, but the claimer of this AU can switch it around a bit if they'd like:

- Becomes a normal height

- Darkness gathered on his head that looks like his hair actually turns into his hair

- Gains skin and actual colors (gets his normal skin color and hair color, eyes stay the same)

- Gains bones (like seriously he doesn't have bones before this XD)

- Gains organs, nerves, and blood (he has to get used to suddenly being able to feel pain lol)

After Orange/Rainbow takes him in, literally everyone soon hears about Sabre through trades routes and such. They're very surprised about him, because... Well, a friendly Darkness is extremely unusual, and it turning into a person even more so. However, they're all very accepting of him as he isn't a threat towards them.

By the time a little after Orange turns into Rainbow, the only hint of him actually being Darkness is his eyes and insides, his blood and other things being black while his eyes have stayed the same the entire time. Sabre gets the blindfold as he knows his eyes tend to scare people because... Darkness. 

Fast forward much, much later, after Rainbow is absorbed by Void and he's in the Hub after Void just killed Funny. Void tries to use his plan, and as usual Time is frozen in fear as Sabre screams out in confusion and pain.

However... things don't go according to plan at all for Void.

When it's all over, Sabre steps backwards, still himself. His blindfold has slipped off his face amid the panic. Confused, he looks around, and there on the ground is a dark, deformed, small figure that resembles a person. Exactly as he used to be.

The small thing looks up at Sabre, its eyes not focusing. Sabre picks it up carefully, looking at it with a kind of recognition. Void is obviously confused, and starts trying to order Sabre around as he is Darkness.

However, both Sabre and the new, small deformed Darkness look in Void's direction, and have the exact same response (as Shadow tries very hard to focus his eyes):

(I was too lazy to draw the bg)

Sabre and Time quickly run off and teleport back, with the surprise that Sabre has a little brother now.

Instead of being corrupted, Sabre helps Shadow form into a person just as Rainbow helped him. I was thinking that there could be a wholesome moment between the two when in the future, Sabre tells Shadow about how he put aside his grief for his best friend to take care of him :3

As he grows into a person like Sabre, Shadow becomes like a more energetic version of his older brother (like every little sibling is). He's nice to everyone, even though he's a bit of a troublemaker sometimes. And everyone's nice to him, because like Sabre, he's not a threat to them.

When it's found out that Shadow can create a sword out of nowhere (the Shadow Sword lol), everyone thinks it's pretty cool. Sabre jokingly says 'No fair', but Shadow decides that he's gonna share the Sword with Sabre then.

By the time the Rainbow Kingdom is created, Shadow is almost fully formed. He is, however, forever a little shorter than Sabre. Things go on as usual, they stick together through everything.

I was thinking that the whole arc about the Demon Steves could go differently, because unlike normal Sabre, in this AU Sabre doesn't keep things to himself as much and asks people he trusts about things he doesn't know. When he and Shadow start seeing them, Sabre actually talked about it in front of the Leaders, and Blue was like 'I'm sorry whatchu say?'

Shadow isn't a traitor here, he would never even think about it. He does still steal the kill during the final battle with Void, but that's because he was angry and wanted to get this fight over with so Sabre didn't get hurt anymore. I'm not kidding when I say Shadow pounced on the guy from above.

Fast forward (again) to the end of the series. Sabre and Shadow know about Origin's visits to them, but they don't know why. Come to find out that they're the way they are because they each have very special artifacts within them;

Sabre has The Origin with him. What happened is that when the loop began, Sabre and Origin watched over the Realm together. When the war with TFC happened, Sabre was killed. Not knowing what to really do, Origin made him a grave at the spot he first created him, burying Sabre with The Origin as he believed it rightfully belonged to him. As time went on, the place he was buried turned into a cliffside, The Origin buried within it. When the Darkness started creating new creatures inside that cliff, it accidentally dragged Sabre out of his grave and gave him new life as a Darkness. You know what happened next.

Shadow has the Heart of the Void with him. It wasn't really destroyed when it was thrown in lava, and Void recovered it when making his volcano lair. Instead of using it for himself, Void decided to use it to try and make a copy of Sabre that would listen to him. Obviously, that didn't work.

Discovering that was kind of a shock to everyone, even Sabre and Shadow of course. Would they try and take them out? Would they be scared to? I won't know, because I'm leaving the rest of the AU up to who claims it :)

Yeah I'm ending it here lol, here's a few situations:

—

(Rainbow Kingdom. Sol doing his speech in the middle of the Kingdom.)

Shadow: (Has to be held back by Sabre and Light because he's trying to run up to that podium and beat the crap outta Sol for talking smack about his older brother)

—

(Sabre gets injured during the time he's helping Shadow become a person.)

Sabre: (Whispering to Shadow) Enjoy not having nerves while you can.

Shadow: Ok?

—

(This is when the Blue Leader finds out there is a problem with the burnt bois.)

Shadow: Yeah, it's weird. I thought it was just me.

Sabre: Nah, I see them too. They keep messing with stuff.

Shadow: I wanna fight 'em.

Sabre: Me too... for some reason-

Blue Leader: (Walking in) What are you two talking about?

Sabre: I think it's just because we're not Steves, but Shadow and I have been seeing these burnt-looking things around a lot. No one else sees them even though they're messing with a lot of stuff.

Shadow: Yeah, what he said.

Blue Leader: (panik) oH. Uh- okay. I'll just-

(Blue Leader runs into the hall, going to get Indigo because there is a problem)

—