Was looking at a game called Roseblight, and got inspired!

What if Shadow was always with Sabre, in a case of two souls sharing one body? Also, Shadow is a good guy here, no villain arc :)

How it would work is Shadow would only appear in reflective surfaces, like mirrors, most of the time. If he wanted to be seen, he would appear next to Sabre like a spirit. He can also take over their body, if Sabre lets him or if it's an emergency. If they're affected by something, for example if one of them is knocked out, the other will automatically have control while the one being affected is recovering. It would take a while for everyone to warm up to him, but eventually he's like one of the group.

They have even more of a sibling dynamic lol. Here's situations:

—

(Sabre is explaining Shadow to Orange)

Sabre: So, yeah, basically we're just two people stuck in one body. We're brothers, I guess?

Orange: So... is he, uh, listening right now?

Sabre: And seeing what's happening.

Orange: ...Can I meet him?

Sabre: Uhh, I'm gonna have to ask him, he's kinda shy-

Shadow: (Appearing next to Sabre) No I'm not, screw off, I just don't like people.

Sabre: There he is.

(Orange just stares at Shadow for a bit.)

Shadow: (Whispering to Sabre) He thinks I'm Darkness, doesn't he?

Sabre: (Whispering to Shadow) No, I don't think so, just wait.

(Orange jump-hugs Shadow)

Orange: Another friend!

Shadow: Wait, you don't think I'm weird?

Orange: Dude, all three of us are kinda weird. I don't mind you!

(Three friends :>)

—

(Yellow Guards attempting to get Sabre and Orange to follow them, these are the guards that are with the actual Yellow King)

Yellow Guard: It'd be a shame if your little friend was hurt...

Sabre: What-

Orange: Huh-

Shadow: (Popping up outta nowhere) Ex-fricking-scuse you?

Yellow Guard: WHAT THE-

Sabre: Oh hey, Shadow.

(They eventually followed)

—

(Fight with Dark in the field, Dark shoots a fireball and it hits Sabre, burning him pretty badly and knocking him to the ground)

Orange: SABRE, NO!

Dark: Huh, missed.

(A grey, cloudlike shroud covers Sabre)

Dark: What the- ?!

Orange: Ohh, so that's what that looks like.

(Shadow is now in control and gets up from the ground)

Shadow: THERE'S TWO SOULS IN THIS BODY, IDIOT!

Dark: WHAT THE-

—

(Nightmare trapping Sabre and Orange in his secret lab. Nightmare is working on things in the other room.)

NM: Alright, now how-

(Sabre, Shadow, and Orange bust through the wall)

Sabre: Hey Nightmare, you forgot something.

Shadow: (Charging an attack) HOW DARE YOU!

Orange: Seeya, wouldn't wanna be ya!

NM: OH SH-

—

(Time and Elemental compare their siblingship to Sabre and Shadow's)

Elemental: Wait, you two just... tackle each other all the time?

Time: And... insult each other?

Sabre: Yup. It's kinda just the way we work.

Time: Doesn't that hurt, though?

Sabre: For him, maybe. He always misses when he tries to tackle me.

(Shadow suddenly rockets from their left, aiming for Sabre)

Shadow: WHADDUP DOOFUS?!

(Sabre ducks, and Shadow crashes nearby into a bunch of boxes, turning into a pile of limbs and pain. He's still laughing, though.)

Sabre: 'Sup, dummy. (Turning back to Time and Elemental) So yeah, that's just us. It gets to this point eventually.

Elemental: ...O-kayyy?

—

Here's some storytelling now :)

As Void, Soul, and Corruption acted on their sinister plan, Sabre was on the ground in pain, Time frozen in fear. As the Darkness corrupts the last few parts of Sabre's soul, a dark shroud covers him, seeming to be a part of the corruption. When it passes, there is a darker version of Sabre taking his place, a person only Time recognizes.

"Good," Void says, grinning as the success of his plan. "It's worked."

Void reaches to drag the new figure up off the ground, when the figure's hand shoots up and grabs Void's arm, twisting it in a painful motion , nearly breaking breaking it. Soul and Corruption look equally surprised, as Void lets out a screech of injury. The figure now stares him in the eyes, starting to get up.

"There's two souls in this body, punk." Shadow growls, pushing Void backward.

Not knowing what else to do, Void and his two henchmen retreat as Shadow prepares to attack. Once they're gone, Shadow turns to Time.

"You okay, Time?" He asks.

"S-Shadow?" Time says. "Yes, I'm okay, but... what happened?"

Shadow looks grim, then starts to explain.

"When Void started corrupting Sabre, I had to fight my way into control." He says. "I was able to get it just before Sabre was fully infected. However, there's still damage..."

Shadow puts a hand to his heart, signaling to Time that something is wrong.

"What did he do to Sabre?" Time asks, now putting his hand on Shadow's shoulder.

Shadow looks like he's about to cry. "It seems Void was corrupting Sabre by forcefully disabling his consciousness, then making Darkness start taking over as he was passing out. I don't know how much exactly, but it's damaged his soul pretty bad. I can barely feel his heartbeat..."

"Then we need to get you two to the others, and fast." Time says.

And with that, they teleport back to the bunker.

As soon as everyone sees Shadow is in control instead of Sabre, they know something is seriously wrong.

"What happened?! Where'd you guys go after the funeral?!" Elemental asks, running behind Time and Shadow.

"Questions later, Elemental!" Shadow says. "Right now, Sabre's in danger!"

The three rush over to the building where they know Blue and Green Steve are, and Shadow bursts through the door. Shocked, the Violet Leader (who is also in the room), starts asking questions.

"Shadow?!" He exclaims. "How- what happened?!"

"Sabre tried to look for something at the Hub, I dunno what, and Void was there." Shadow says. "And Void found a way to try and corrupt him. He almost did, then I jumped in."

"What happened to Sabre?!" Green asks, already grabbing what he knows is needed for a soul-healing situation, Blue doing the same.

"Shadow says that his soul is really damaged." Time says.

"How bad?!" Blue says, already seating Shadow down so they can start helping Sabre.

"I don't know exactly, but it's bad." Shadow says.

Shadow brings out his and Sabre's souls, a soft white glow illuminating the room. While his looks fine, Sabre's is almost covered in an ebony black, cracking and shuddering. His soul's beat is barely keeping up with his brother's. Horror envelops the room.

"Oh my goodness..." the Violet Leader gasps.

Green Steve turns to Time and Elemental.

"This is gonna take a while, you two. Go ahead and... I dunno, just go."

Time and Elemental understand, and leave the building. As they do, Time takes one last look at Shadow. He's actually crying now.

It takes a while, just like Green said. Time and Elemental have been waiting outside for at least two hours. Worried friends have asked what happened, and they explained. Now that the word was out, the whole Bunker was waiting for news of Sabre's health. Just when they're about to go and check in themselves, Time and Elemental see Shadow leaving the building, a strange device affixed to his arm. He sees them, and walks over.

"Is he... alive?" Elemental asks.

"He is, thankfully." Shadow says. "Unfortunately, he's gonna take a long time to heal, so you're stuck with me for a while."

Time and Elemental breathe a sigh of relief. At least Sabre will be alright.

"What's the thing on your arm for?" Time asks.

"Oh, this..." Shadow says, looking at the device. "It's connected to Sabre's soul. Sabre was still conscious through all of that, and in a lot of pain... in order to make sure he heals properly and to keep him from suffering, this thing will basically keep Sabre asleep until he heals."

"Oh..." Time says.

That day, they all silently swore to be there when Sabre awoke. They didn't know when, or if he ever would, but they stuck to each other's sides from that day.

It's been months since the incident. A grave had been made for Funny, in the meantime, as his death was the reason Sabre went haywire. Everyone else had given up at least some hope that Sabre will return, except Shadow, Time, and Elemental. Sitting at Sabre and Shadow's house, they're being visited by Yellow Steve (the one with the leather chestplate).

"I'm just saying guys, it's been a few months." Yellow says. "You shouldn't get your hopes too high, just in case."

"Screw that." Elemental says, leaning against the wall.

"Ditto." Time answers his brother. He's sitting down, having some tea.

"Sabre will wake up soon, I know it." Shadow says, laying on the floor. "Yeah, it's been a while, but I'm not giving up on him."

"I'm not either, you three," Yellow continues. "But you gotta just accept that it might go wrong, too."

Shadow stares Yellow straight in the eyes, or at least looks like he does.

"I will wait 'till the day I die if I have to." He says, completely deadpan.

Yellow sighs, and everyone goes silent for a few minutes, just contemplating their situation. Darkness is still running rampant, although they've been able to move out of the Bunker and into the Hub. Shadow has gained much more trust from the Steves at this point, as he's been helping with defending against the Darkness during supply runs and such. He's even started helping out the new Colorless Guard that Light had become captain of. Shadow's thoughts are interrupted, as he feels a second heartbeat jump from almost dormant to beating quickly. A heartbeat he hadn't felt in a long time. He shoots up from laying down, a hand clasped over his heart.

"What is it, Shadow?" Time asks, worriedly.

Elemental and Yellow rush over to Shadow to calm him down.

"Easy, bud, what happened?" Elemental asked, his hand on Shadow's shoulder.

"I-I- Sabre. I felt his heartbeat just now. I swear, I did." Shadow says, panicking, but in a kind of good way. He's speaking too fast for everyone else to understand.

Time joins the two other in calming Shadow down.

"Calm down, Shadow. You're going too fast. Slow down." Time says.

"Sabre! He's back! I-I felt his heartbeat a second ago! It's still going!" Shadow says, slower this time.

"What? Are you sure?" Yellow asks.

"Yes, I'm sure!" Shadow says. "I swear, I did! He's back!"

"There's no way, he's been out for months, remember?" Yellow says.

Suddenly, a familiar voice rings out from behind them.

"Aw, c'mon Yellow, you know I don't go down that easy."

The four turn around, to see an old friend, still wearing the same cheesy grin he always has. He just looks a little more like a spirit now. Shadow springs up, running to him and tackling him in a hug.

"Sabre! It's really you!"

Sabre wraps his arms around his brother, returning the hug.

"Hey there, buddy. How ya been?"

—

Y'all, I might keep this one too lol. I'm sorry, but I keep making them too good and getting attached XD