Regret.

That's all Levi Ackerman could feel as he stood, breathing heavily so that he might regain his breath, staring down at the remains of what were once his friends. Behind him, the deceased Titan lay, blood forming a pool at the former's feet, from the violent slashes he'd delivered to the Titan.

He had failed, so miserably, and it was too late to do anything. If he hadn't gone on ahead to carry out a plan so far-fetched, they would still be here. But he was selfish, and ignorant. Now, he stood, unable to keep tears from falling down his face, something that had never happened to him before. He wished he were dead.

Earlier that day…

"Today we take another step forwards, to winning this fight!"

Levi was hardly listening, his gaze focused solely on the opening gates. In a few minutes, he would be beyond them, in the bright light of the outside world. What horrors lay in wait? He could only wonder, as he preferred not to know until the time arose. The dark horse he sat upon sensed his uneasiness and nickered.

"Let us show these Titans the strength of humanity!"

Levi finally averted his gaze to focus on the speaker, the leader of the 23rd Expedition, a tall man with dark hair and shadowed eyes. It was time.

The gates opened. "Forward, everyone!" The horses took off through the tunnel, and once they passed through, spread out into battle formation.

Trees stood tall, and rolling fields of green surrounded them. The air was cool, and slightly humid, indicating a possible rainstorm.

"Wow!" Isabel marveled from a few feet away. She was perched atop a sturdy gray horse, and she stared into the pale blue sky, her eyes shining. "It's beautiful out here!"

"Yeah," Levi found himself saying. "Not bad at all…"

Beside him, Farlan grinned, nodding in agreement, his blonde hair ruffled by the breeze. They rode onwards, on the lookout for any Titans that might cross their path when suddenly…

"Titan sighted!"

Levi's eyes widened as it came running at them. Titans were no joke to be told. They were huge, at least eight meters tall, with human faces. Before he had any time to contemplate anything, the others advanced. Isabel and Farlan watched in fascination as they used the 3d-maneuver gear and took off, leaping from their horses. Levi winced as one overly confident man plowed straight forwards, only to be snatched out of the air by the Titan. There was no mistaking the horrifying 'crunch' as the man met his end. No time to stop and mourn, because two 10-meter Titans were rapidly approaching.

Levi quickly pulled the reins on his horse and swerved to the left, before turning it around. He took off towards one of the approaching Titans. Now was his chance to kill one of these horrifying monsters.

"Is he trying to get himself killed?!" He heard someone shout, but Levi ignored him. He shot the wire from his gear into a tree just past the Titan and leapt forwards, gliding around the Titan before soaring high and delivering the killing blow to the back of its neck. He watched with satisfaction as the Titan crumpled to the ground.

Meanwhile, Isabel and Farlan were taking on the other Titan. Levi pitched forwards as Isabel was grabbed by the Titan, but she slashed its hand.

"Nice try, loser!" She laughed as she leapt from its grasp. Farlan swung around the Titan's head to deliver the killing blow. As the Titan fell, Levi could only stare in shock. He had never known his friends to have such unwavering determination. He was the one at fault here, for not believing in their abilities. Rain drops began to soak the ground, and Levi swore not to underestimate them again.

…

But then he made a choice he never wanted to make. He had abandoned his friends, when they needed him. He had blindly passed a Titan, and when he had returned, it was too late. His horse stumbled in the mud as rain poured down, throwing Levi from its back. As he struggled to his feet, his eyes widened in sheer horror.

Two lifeless eyes stared back at him, her brow furrowed, and her mouth curled in a snarl. Isabel. Thump. Levi could only watch as Farlan hit the ground a few feet away, his eyes staring lifelessly up at the sky, now a vast space of murky gray.

Levi felt his blood boil as his unimaginable hatred for the Titans grew. "Damn these Titans." He threw his head back, ignoring the raindrops that pelted his face. "IS THIS WHAT OUR ONLY PURPOSE IN LIFE IS? LIVE, ONLY TO DIE AT THE HANDS OF THESE RAVENOUS BEASTS!?" He lowered his head, glaring at the Titan at fault. It's beady black eyes stared back at him, unaware of the bloodlust.

With a scream, Levi leapt at the Titan, and spared him no mercy. Slash after slash, Levi yelled as he rained his blades down on the Titan. YOU MORONS, YOU DON'T KNOW WHAT YOU MAKE US LIVE THROUGH. WHY?! WHY US! When at last the Titan fell to the ground with a crash, Levi stood, feeling anything but victorious, staring at the remains of what were once Isabel and Farlan. Deep down, he knew, he was too blame for this. All of it.

…

When I watched the spin-off, No Regrets, I knew I wanted to write this. I'm writing based off of the anime adaptation and for my own entertainment to get my ideas out there. I'm not into happy, bubbly AoT fics, hence the genre of this story. Levi is one of my favorite characters, because of his complex background and he's so badass. Thanks for reading!

Ps: I'm aware of the Furlan/Farlan situation, I prefer Farlan.