A broken mind

Just like in the original anime, everything unfolded according to canon. Today would be the day of the 56th expedition outside the walls. Over the past few days, Kazuya had gotten closer to Eren and his friends, building bonds and disguising his intentions. Looking around, he saw the worried faces of the soldiers, aware of the imminent danger. A crucial difference was that Annie had joined the Survey Corps.

Exchanging glances with his three temporary allies—Reiner, Annie, and Bertolt—they nodded slightly. The capture of Eren was about to begin.

Erwin Smith rose on his horse and raised his hand to draw everyone's attention. The murmurs ceased. "Soldiers of humanity!" he began, his powerful voice echoing over the formation. "Today, we venture beyond the walls once more to face the enemy. We don't know what awaits us, but we know what drives us. It is not merely the desire to survive, but the desire to discover the truth! The desire to protect those we leave behind! Our mission is clear: advance and survive! Sacrifice our lives, if necessary, to ensure humanity has a future!"

Shouts of "Yes, sir!" echoed across the field. "Follow the plan! Follow your leaders! And remember... victory belongs to those who seize it with their own hands! Onward!"

The expedition had begun. The squads of the Survey Corps scattered, taking the standard scout formation, while the central units organized around Eren and his group, offering solid defense against any threats.

Unfortunately for Kazuya and his temporary allies, they had been assigned to different squads. However, luck was on Kazuya's side: he was placed in the squad closest to Eren, personally chosen by Levi to provide support in case something went wrong.

Reiner, on the other hand, was in the group that included Armin and Jean, which complicated things. Annie was positioned next to Mikasa, along with Bertolt, a pairing that was far from ideal. Kazuya had warned Annie not to transform into a Titan or attempt to face Mikasa directly.

"The Ackermans are a headache..." Kazuya thought to himself, casting a glance toward Levi.

*

Reiner's mind was a whirlwind as he rode alongside Jean, Armin, and two other members of the Survey Corps. Kazuya's words echoed like a drum in the depths of his consciousness, and he knew the decisive moment had arrived. His breathing was heavy and uneven, and his heart pounded furiously, as if it were about to explode in his chest. He couldn't stop thinking about what he was about to do, the impending betrayal.

"Reiner, are you okay?" Armin asked, noticing the distant and disturbed look on his face. "You seem... different."

Reiner clenched his fists, trying to fight against the rising tide of guilt and confusion that threatened to drown him. He didn't want to do this. He didn't want to see the fear, disappointment, and horror on his comrades' faces. But the orders were clear, and he knew there was no other option.

"Reiner?" Jean called, his voice filled with concern. "What are you thinking? Why are you trembling?"

It was now or never. Reiner bit his own hand hard, and the sound of bones breaking reverberated through the air. The shock of the transformation resounded through the forest like thunder. His body exploded in size and strength, his eyes burning with desperate and painful determination. The Armored Titan rose, and chaos erupted in an instant.

"Reiner?" Armin shouted, his voice filled with panic, as the shockwave of the transformation pushed him back, along with Jean and the other two comrades. The air around them distorted with the sudden force of the blast.

Everything happened too fast. In one second, they were riding together, and in the next, a colossal Titan stood before them. The shock and surprise turned hope into despair. It was terrifying to discover that Reiner could also transform into a Titan.

"What the hell is this?!" Jean shouted, his heart racing. The other two squad members muttered words of fear and confusion, trying to get up from the ground, adrenaline already rushing through their veins.

"Wait, stop! It's Reiner!" Armin shouted, trying to stay calm, but deep down, he knew this revelation would only compromise his comrades' minds. And he was right.

The soldiers hesitated for a second, their faces showing a mix of disbelief and terror. But a second was all Reiner needed. Taking advantage of the confusion, the Armored Titan charged with devastating speed.

The first blow was a brutal kick that shattered the ground with a bang, sending Jean and the other two comrades flying like rag dolls. The force of the impact was relentless. Jean was hurled violently against a thick trunk, his body breaking at an impossible angle. He was crushed against the tree, his blood splattering like a red blur on the surrounding leaves.

The other two comrades met equally tragic fates. One was hit directly, his body bursting like a smashed watermelon, pieces of flesh and bone scattering across the forest.

Seeing the shattered bodies of his comrades, Reiner entered a frenzy that completely consumed him. The mission given by Marley, the identity he had assumed as Marcel, the life he had pretended was his as an Eldian within the walls—all of this collapsed upon him at once, crushing his sanity. The Armored Titan, gigantic and imposing, brought his hands to his head in a gesture of absolute despair, while an inhuman scream tore through the air.

"Jean, everyone... I'm sorry," Reiner's voice quivered within the Titan's body.

Armin watched everything with wide eyes, tears flowing uncontrollably. Panic overtook him, and he vomited, clutching his own stomach.

"What the hell is happening?" Armin thought, his mind in collapse. He had just discovered that one of his friends could transform into a Titan, and Jean was dead.

He tried to stand up, but his legs were trembling. On his second attempt, he managed to walk a few meters, trying to call his horse, but he fell again.

"Damn, my legs," Armin muttered, trying to get closer to the horse.

Reiner, in a moment of clarity, saw Armin stumbling toward the horse. He was lost. Should he kill Armin? Spare his life? His mind was in conflict.

"Marcel, what do I do?" Reiner wondered, completely disoriented.

After a few seconds of contemplation, Reiner made a decision. He couldn't kill Armin. He was too confused; all of it was too much for him to process.

"At least I eliminated three. They won't get in our way," Reiner thought, watching Armin.

He looked at the bag Armin had dropped while stumbling. With a heavy step, Reiner crushed the bag, releasing a small cloud of smoke.

"Now, he can't warn the others."

Reiner ran toward the squad where Eren was. Taking the opportunity, he kicked Armin's horse, sending it flying away. He didn't look back. He couldn't face Armin's face again and hoped he would never have to.

Armin, on the other hand, sat on the ground as tears continued to flow. Reiner had spared him, and he didn't know why. Seeing his horse being killed, Armin realized he had no way to reach another squad to warn them.

"Guys, be careful" Armin murmured, starting to walk toward Eren's group. Even without the horse, he still had his own legs to try to reach his comrades. At the very least, he had to try.