Accept it
"You just had to tempt fate, didn't ya? That's why your life went down the shitter ever since you screwed over the track team!" Shadow Ryuji sneered as it delivered another swift kick to Ryuji's stomach.
A metallic smell overwhelmed Joker's senses as he helplessly looked over to his comrade. From his current position, Joker could wriggle his arm out from underneath one of the shadows and aim his gun, but he knew that he wouldn't have a clear enough shot at the thing that wore Ryuji's face.
Ryuji drove his fingernails into the ground and desperately tried to push himself back to standing height, however the pain blossoming across his body begged to differ and the copper taste that thickly coated the inside of his mouth threatened to make him spill the contents of his stomach. He looked up towards the creature that stood and growled the anger coursing through his veins overpowering the pain he felt. He swung his arm out sloppily attempting to strike at his shadow with a right hook, but the pounding in his head and lack of coordination meant that the shadow could easily shuffle to the side.
It cackled as Ryuji collided harshly with the dirt-covered stone flooring and proceeded to stomp his foot below the poor boy's right knee joint, "Kamoshida let you off too easily... If I was him, I'd break your leg over and over. Until. You. Knew. Your. Place!" Shadow Ryuji yelled punctuating his sentence with an onslaught of stomps onto the weakened leg with each stomp stronger than the last.
Luckily for Joker, it had positioned himself in the perfect place for him, he aimed as best as he could whilst ignoring Ryuji's howls of pain and cries of agony and opened fire. The Shadow version of Ryuji yelped in pain as the bullets struck his shoulder and left side. In that moment of weakness, Ryuji grabbed his counterpart's leg and pulled him down to the ground and immediately pounced upon him striking his shadow anywhere he could with his fists until they were bloodied and bruised.
The shadows distracted by the sudden surge of strength from the other prisoner failed to realise that the Joker had abandoned his coat and slipped out under their grasp. They turned their heads at the sound of a sharp whistle from behind them and saw the Joker smirking with his fingers poised over his mask. Joker called Arsene's name and quickly disposed of the weaklings before approaching Ryuji.
Shadow Ryuji now covered in hideous blotches of purple and blue grinned at the real him that was heaving for breath and had a shaky fist ready to slam into his face and laughed at the pained expression the real Ryuji wore, "That's it. Take a good long look at me. Looks familiar, huh? Doesn't it look like the time Dad beat us within an inch of our pathetic lives?"
Ryuji's fist tightened and as he was about to respond the sudden softness of Shadow Ryuji's tone caught him off-guard.
"You know what happened next right?"
Ryuji's breath hitched and his eyes stung, as his arm slowly came down and dangled by his side, he whispered and begged quietly to his shadow to stop, but the creature kept going.
"The way that Mom had to intervene and that resulted in her getting them stitches on her forehead? Now look at me and see that this was the face Dad saw… You did this. You're becoming the monster you hated so much! So, is Mom gonna be next, huh!? Is it gonna be her when you lose your temper!?"
The yell of white hot rage that erupted from Ryuji's chest could only be described as the sound of a feral wolf striking at its prey, as Ryuji grabbed his shadow by the chain around his dog collar and threw his right fist forward.
Joker's hand had grabbed Ryuji roughly by the elbow and sharply jerked him backwards, "You're giving it what it wants." He spoke carefully watching his comrade's frame shake with boiling fury. Joker's gaze locked onto the Shadow version of Ryuji and glared at the sight of the unshaken smugness in it's smirk and the triumph glowing in it's topaz eyes. He sighed before continuing, "As much as you hate it… It's part of you. You need to accept it."
Ryuji's expression contorted itself into one of anguish and reluctance and glanced over his shoulder to meet the serious look in Joker's eyes. He turned his gaze back to the arrogant smirk on his shadow's face and growled, before gritting through his teeth, "There's no way in hell that I'm accepting this bastard." He grimaced as the Shadow began to laugh and grin even wider and felt Joker's grip against his elbow tighten in warning. Ryuji pondered for a moment and allowed his mind to mull over the words his shadow had taunted him with earlier. He cleared his throat and mumbled something under his breath that made his shadow freeze in disgust. Defiantly, Ryuji raised his head and met his shadow's gaze dead on and repeated himself his voice ringing out throughout the cell clearly, "But I guess I gotta so I can make up for what I've done."
Author's Note: So this idea came to me whilst discussing the possibility of the P5 Phantom Thieves getting shadows like the cast of P4 did in Shenpai's server. I highly encourage you guys to go check out her work over on Tumblr and her streams/videos on YouTube and Twitch since her and her fans have inspired me to try my hand at writing a drabble fanfiction after so long!