Transmigrated As The Bastard Side-Character

...

The walk deeper inside felt strangely intriguing, and every new section of the caverns somehow made their movements lighter as curiosity slowly overtook caution.

One moment, they were walking beside a narrow river cascading peacefully along the edge of an empty stone path, and the next, they found themselves staring at skeletal remains scattered across the floor.

Some bones were floating just above the surface of a dark pond as if the water itself refused to claim them.

Ren swallowed nervously, the butterflies in his stomach only multiplying with every step they took.

"These caverns really don’t end, huh?" Cassien muttered while glancing over his shoulder.

Creak.

"AHH!" Ren nearly jumped out of his own skin. "W-what was that?!"

Cassien immediately grinned. "No way..." he whispered dramatically. "We’re all about to die."

Ren instantly started panicking until Aiysha pressed a finger against his lips. "Cassien, stop messing around. Now isn’t the time."

Cassien scratched the back of his head awkwardly. "Sorry."

Since they still hadn’t encountered a single beast or anything remotely resembling a Demon, the group continued moving deeper inside without much hesitation. After a while, Victoria suddenly removed the backpack she had been carrying this entire trip.

"Anyone want ham sandwiches?"

...

Naturally, everyone accepted immediately. She handed each of them a sandwich alongside a bottle of water, and the atmosphere became oddly casual as they all sat down on nearby rocks to eat.

Victoria glanced specifically toward Cassien while adjusting a loose strand of hair behind her ear. "So..." she asked quietly, "What do you think?"

Cassien continued chewing before answering. "It’s good. Nice flavor."

Victoria visibly relaxed, placing a hand over her chest. "I’m glad."

Ren dramatically raised his hand. "What about me? I also think the sandwich is amazing!"

Aiysha let out a small laugh at his enthusiasm, while Cassien simply watched all of them for a moment. This weird little group somehow felt absurdly normal. A princess obsessing over him, an aggressive swordswoman, and a socially awkward protagonist all casually eating sandwiches inside what was supposed to be a death cave. It was ridiculous. And somehow... comforting.

"I wish moments like this could last forever," Cassien muttered under his breath. "I’d do anything to keep this."

Aiysha slowly lowered her sandwich and stared at him. "...You good?"

Cassien blinked. "What?"

She awkwardly pointed toward his face. "Dude. You’re literally crying."

Cassien paused before touching beneath his eyes, only to realize actual tears had begun streaming down his face. He stared at the moisture collecting against his fingertips.

"Oh."

Aiysha looked mildly disturbed. "I genuinely didn’t think you were capable of human emotion."

"This is new for me, too," Cassien admitted.

Victoria immediately looked horrified. "Was it the sandwich?"

Cassien quickly wiped his face. "No. It’s just..." He looked away for a second. "Life, I guess."

...

Eventually, the group resumed walking until they arrived at what appeared to be a split in the path. Two massive openings stood before them, each leading into entirely separate tunnels.

Aiysha crossed her arms. "Men with men. Girls with girls."

No one really argued with that logic.

"We’ll take the left tunnel," Cassien said. "You two can go right."

Victoria nodded, though before they separated, she gave one final instruction. "If anything feels too dangerous, scream for help or retreat immediately. Don’t force anything. Just gather information and come back here so we can regroup."

Honestly, it was probably the smartest suggestion anyone had made all day.

...

With that, the group split apart. Cassien and Ren entered their tunnel while the girls disappeared into the other route.

"Ren, get in front," Cassien instructed. "You’re better suited for close-range combat."

"G-got it." Ren gripped his sword nervously while scanning the darkness ahead. "You really think splitting up was a good idea?"

Cassien shrugged. "It was their suggestion."

SLAM!

Both of them froze instantly. Ren turned around so quickly he nearly tripped over himself.

"Fuck, fuck, fuck—"

Their exit had completely collapsed behind them, jagged rocks now blocking the tunnel entirely. Ren immediately infused mana into his blade and repeatedly slammed it against the rubble, but nothing happened.

Cassien calmly stepped closer to inspect the stones. "No use."

Ren stopped mid-swing. "...Why?"

"These rocks are deflecting mana somehow."

Ren’s eyes widened. "Then no beast could’ve done this."

Cassien nodded. "Exactly. A person did." He folded his arms. "If I had to guess, probably the village chief."

Ren stared blankly for a moment. "So..." He sighed. "The only way out is forward?"

"Yep."

Ren closed his eyes briefly before inhaling deeply. "...Fine. Let’s go."

Cassien smirked slightly. ’Character development. Good job, protagonist.’

Step. Step. Step.

The two continued forward, and the walk somehow felt even more endless than before.

"You think the girls are okay?" Ren asked quietly.

Cassien shook his head. "Most likely the same thing happened to them too. We’re probably all trapped now."

Ren tightened his grip around his sword. "How are you this calm?"

Cassien casually reached into his coat and pulled something out. "Because, unlike you, I remembered to bring a torch."

He infused a small amount of mana into the mana-absorbing torch he had borrowed from Victoria earlier, lighting up the darkness around them. The warm glow illuminated more stone, more empty tunnels, and still no beasts.

"No enemies yet," Cassien muttered. "That’s weird."

...

Eventually, they arrived somewhere new. The tunnel opened into an enormous cavern, far wider than anything they had seen so far. The ceiling stretched so high it was practically invisible, and directly across from where they entered was another tunnel opening.

Cassien narrowed his eyes. ’That probably connects to the girls’ route.’

Ren stepped slightly in front of him while thinking out loud. "What if the Demon only appears once people arrive from both tunnels?" He awkwardly paused. "No, never mind. I’m probably overthinking again."

Cassien shook his head. "No, that’s actually a solid theory." He leaned casually against the wall. "Let’s wait ten minutes. If nobody comes through that tunnel, we move on."

...

Ten minutes passed. Nothing happened. Only the two of them remained.

Cassien sighed. "Keep moving." He casually checked his pistol for a second. "No point waiting anymore."

Ren nodded and continued walking forward while Cassien lingered slightly behind.

"You go ahead for a second," Cassien said. "I’m checking something."

Ren looked visibly uncomfortable. "Just... don’t leave me alone here."

Cassien nodded, and his eyes naturally drifted toward Ren’s back. It still felt strange traveling alongside him. The future hero of this world. Ren Castor. The man fated to save everything.

Or rather—

Zink.

Cassien’s body suddenly dropped low against his own will, his knees nearly buckling beneath him.

"What the hell—"

A sharp pain shot violently through his side, so intense it nearly forced the air straight out of his lungs. He immediately clutched his abdomen, his vision blurring almost instantly.

A notification appeared.

→[System Detected Wrong [Fated] Callout]

[Side Effects]└ Feel the equivalent pain of being stabbed through the side abdomen.→

Cassien’s breathing became uneven as the pain continued pulsing through his body. It was real. Horribly real.

"U-uh, Cassien?" Ren turned around. "Hurry up. What’s happening?"

Cassien forced himself upright slightly, coughing once. "J-just... give me a second."

His vision slowly began stabilizing, and once he finally forced himself to look up again, the illusion shattered completely. Everything clicked into place all at once.

The person standing in front of him this entire time... wasn’t Ren Castor.

He had never been Ren Castor.

Cassien stared in complete disbelief. For the first time since arriving in this world, he had been fooled. Completely.

"Come on, Cassien."

The fake Ren smiled faintly.

"We have to keep moving."