A/N: this is my first time writing a fanfiction that features Ereri/Riren. I've always wanted to write one but never really had the time to do so. Hopefully, you readers will like the story. Reviews are very much appreciated. Now onto the first chapter–

Disclaimer: I do not own Shingeki no Kyojin. If I did I'd make Levi creep on Eren 24/7 and deny the fact that he sleeps with the younger boy's underwear on.

Least Worst Criminal

By: graylubitches

Chapter One: Transferred to Door S-10.

The clicking of shoes echoed rapidly on the flat surface of the floor as Eren dashed pass the halls (ignoring odd stares from onlookers) and halted to sedate his pace only after finally reaching the metal door. He twisted the knob—and not even a minute passed when a loud howl of cheer escaped his throat. "Promotion? I got a promotion?!" he said in ecstasy while pulling his wallet out (from a secret pouch underneath his jacket), particularly a familiar photo inside, before planting kisses on said treasure. "Mother, what did I do to receive such a heartwarming gift from you? I pray to you my guardian angel; I will work hard and earn money for our family!"

A brunette woman in the picture continued to smile at him and a bittersweet one crawled across the lad's lips. "If only you were here to see me in my uniform, ma."

Levi's P.O.V:

"–was assigned to a new cell which means you'll be getting a new officer today." Another stinging pain lashed at my back and I coughed up blood. "This will be the third time we have to switch your watchdog." Whipped. "So you better fucking behave this time if you don't want me to shred you to pieces," whipped, "then boil every part of them into a hotpot for the dogs to eat." Whipped. "You're lower than a mutt's level. Do you understand, you worthless scumbag?" I heard the sound of the whip he hit me with being dropped. And in the corner of my eyes, I could see him reaching for the bucket of ice water to follow through with his beating. I'm not dumb to figure out what he was going to do next.

As I predicted, he proceeded to hold the pail above my head and slowly poured the contents out. I growled then quickly gritted my teeth to prevent myself from screaming.

Fuck this bastard! Once I get out from these cuffs, I'm going to kill this dumbass as slow as he did with the liquid, or slower. My shirt stained by his blood and a big socket of eyeball crushed by my own hands. I'll castrate this motherfucker!

After another long period of torture, the man was finally called out for a different duty. I could barely keep my eyes open and knew my body had gone numb because I had not felt the harsh tug I got at my cuffed hands before being thrown back to my hard bed. The bleeding wouldn't stop yet I could no longer feel them flow down.

I began to drift off to a slumber; exhausted from such a shitty day.

Though unconsciously I was already planning a hundred other ways to torment my upcoming officer.

Who thinks I can get this new guy to quit and leave for a different department in two weeks and break my three-week record?

My eyes closed shut.

"Are you sure about this, Eren?" Mikasa asked in worry while gripping onto her red scarf tight. "You know how dangerous it is to work in the Scouting Legion. Only the worst criminals are kept in there."

"Stop worrying," the brunet let out an exasperated sigh. "This is big news, Mikasa. Shouldn't you be happy that my position got moved up, and that we'll be going to the same department? I'm gonna get a higher pay which means I can contribute more to our expenses, and before you know it, we'll have the money we need for Armin's surgery."

The woman looked down and continued to fidget. It was true that they did need the extra money.

Armin—their sworn brother and childhood best friend—got involved in a mishap that no one wished for four months ago, and is currently resting in the hospital. There was a sudden attack from a masked group of people calling themselves 'The Wings of Freedom' (which is total bullshit since they hurt a lot of people) at another hospital place he was at. A victim for rape had stayed there and Armin came by to deliver a basket of fruits and flowers to bring good news regarding the imprisonment of the suspect. He was only trying to be a compassionate policeman.

Then—it happened quickly. A ruckus began which resulted to a bullet striking him close to the heart that left him unconscious for long hours. His condition was deemed to be very serious, and the doctors had to operate on him many times to stop the bleeding. After, they needed to find a similar blood donor for him after losing too much of his own. The process took weeks and even now he is still in harm's way. Armin is in—no was in a coma, when recently a news came up that claimed he had woken up with a sudden seizure but needed another surgery. It's sad that he has to experience the crucial pain with some conscious mind and felt crushed whenever a groan escaped from his mouth.

More money; both Eren and Mikasa thought. They didn't care how much they needed to be spend if it was all going to the chance and possibility of Armin recovering from the damages. They love him. Very much.

But Mikasa still had concerns. "What if something happens to you too? I won't be able to handle it." She needed to have a chat with Chief Erwin and convince the man to cancel the lad's promotion. It was too risky for him to work in such a place.

"You don't have to worry about me," Eren argued with a sharp glare. "I can take care of myself just fine. I worked hard for this promotion. To be able to move up. To prove to myself that I can do better. That I can be better at protecting powerless civilians. Better in making sure those shitholes stay behind bars. Better at what I do as an officer."

"Eren, you're gonna be a watchdog for one of those dangerous shitholes. He will attack you the minute you have your guard down."

"That's just it, Mikasa! You don't trust me. You think I'm gonna fuck up and get myself killed! You think I'm gonna let the bastard escape and let him run around in town once again shooting and cutting people up. I'm trained. I've been trained for two years. And I know I can do this. So enough with you trying to make me feel less than what I am and actually believe in me."

All three of them were recruited as officers two years ago despite their young age with the help of their mother's friend Hannes. He knew they needed an occupation to live a better life, and happily recommended them to the Titan Station. They were tested physically, strategically and mentally. Mikasa got an outstanding perfect score (except for the strategy test which she scored 9/10 on) and was the reason to why she was immediately put to work at the Scouting Legion as a monster rookie. Armin had a score of 7/10 in the physical test while Eren scored an 8/10, then he scored a 10/10 in the strategic test while Eren scored another 8/10, and for the mental test he scored an 8/10 that Eren perfected on.

They were both assigned to a lower department by taking care of the prisoners in the A-Level. It is a high stage according to the pyramid of Least to Highest level: E-A. Of course, despite that fact, he still envied his sister for making it to the S-Level as soon as they started and aspired strongly to be promoted to the same field. And now that it is beginning to come true—he felt very overwhelmed and excited.

"I do trust you. It's that criminal who I don't trust. He's a criminal worthy to be jailed in the Scouting Legion. Which means he's one of the worst who has insanely killed many people before. Someone so inhumane–" she explained but stopped once she saw the upset look Eren had on his face. The boy continued to frown at her words and this made her heart ache. So in defeat and in fear of arguing with him any further, she could only sigh—then reached over to grab his hands. "I'm not okay with this. I'm worried and I'll keep worrying. But if you really want to do this, then who am I to prevent you from stepping into that horrendous building. However, I have one condition. Only one!" Mikasa insisted before Eren could open his mouth to oppose. "You will not in any way let him touch you. If he did so as to dare lay a hand on your precious skin and hair…without lying or keeping it a secret, you will tell me if he did and I'll cut his head off in mere seconds. Promise me."

Eren knew—that is as far as he can go in convincing his sister about the situation so he agreed. "I promise."

The building was huge. Double the size of Titan Station. Probably because if one tried to escape, they will have a hard time from the large space and the many alarms set in every floors. He spotted video cameras in all corners he took and noticed some slightly infrared lighting referring to the alarm devices. The whole place screamed lock-down for prisoners!

Eren followed one of the department heads who's name is Mike Zakarius. They took the elevator to the 10th floor (the centre of the 20th floor building) where he was guided to the very far door of the hall. The door has a sign of S-10 in white painted letters.

They stopped by the door and Mike turned to him to speak. "I hear this is your first day here at Scouting Legion so I'm going to need to explain to you a few things. First of all, I expect great things from you if you are going to prove to me you are worthy of being here. I'm not interested in complaints. Only on simple reports. Like how the asshole caused no trouble and is receiving his punishment well. If you read the rule book, it says that you are permitted to beat the criminal in any way an officer want. I don't want you to make it into a habit of seeing this act as a type of entertainment. Hit him only if he deserves it. He is obligated to drink his medicine after every meal. The pill will basically drain his energy out. Second, you are his watchdog so don't ever take yours eyes off of him. If he escapes even once from this cellar, you are immediately demoted so make sure it never happens."

Eren nodded trying to take in everything in his memory. "Lastly, S-10 is the least worst criminal you will meet so I guess you won't have to suffer much. It goes all the way to S-1 meaning the worst so you are forbidden to go up to any floors higher than this since you lack requirement. Your criminal is named Levi which is why I keep mentioning the word 'he'. You don't need to know why he's in there. Just do your job. Anyway, there has been an issue of sort around him since you are actually the fourth person to be assigned as his watchdog. It's tiring to keep looking for a replacement over time, so I expect you to last at least a little longer than three weeks. You are to work from 6 a.m until 10 p.m. The head watcher will watch over him during the remaining time you are gone, understand? Now go in. It's lunch time so take this with you." Mike picked up a tray (with a cover taped around it messily to act as a lid) from the cart beside the door and shoved it into Eren's arms.

Immediately, although he hadn't completely prepared himself from going in, he found himself on the other side of the door with the plate in hand. His eyes glossed over to a figure who sat directly across from him on the bed. A long chain of lock was around the man's neck and his hands were currently not cuffed together behind the tall and huge bars. Yet he looked at Eren with such a strong demeanor as if he was the superior one.

Eren cleared his throat reluctant to look at the person's gray dull eyes. "I'm your new watchdog starting today. My name is Eren."

He then walked towards the bars and flipped the tray sideways so it can fit in between the metals. It landed on the ground and after, he pushed it closer to the man for him to bend over for, before straightening his stance to just watch. "Eat. Apparently it's lunch time so here's your food."

Levi grabbed the tray from the floor before unwrapping—no ripping the tape off. He threw the lid at the bars creating a banging sound and Eren reached over to retrieve it. It was a bit far from him and the clinging of his keys interrupted his concentration. He looked up at Levi who ate in silence then glanced at his chain. It was connected to the concrete wall and by measuring it with how he visualized the length; Eren concluded that he can get in without the man actually touching him if he remained to the farthest edge of the cell.

Eren opened the bar door and proceeded with his plan. He smoothly scooted to where the cover laid and crouched down for it when a voice conveniently cut itself through air. "I'm eager to stick this spoon inside your pretty damn ass and make you beg for more."

The first words, first sentence, the voice the man had—took Eren off guard. He was shocked that a husky, deep, alluring tone could be possessed by such a tiny man. Shocked that it could send shivers down his spine. But more than shock at what he heard. "Excuse me?"

"I said I want to fuck you with this spoon."

Eren's eyes widened and he dropped the cover. Such vulgarity words! He lifted his head to stare at the man—red all over at the statement that it made Levi smirk in return. "Virgin, I see." Levi stood up gracefully, placing the tray aside and walked towards him. The chain did limit his distance to Eren's relief. The man came as far as within a metre range though it was still pretty close. "How innocent. I would love to screw you right here and right now to take your everything away."

His legs shook and Eren felt himself almost melting at the devious voice. "Come closer." It was so hypnotizing. Levi's voice. Then suddenly, Armin's face popped up in his head and he was out of the trance. "Come to me, Eren."

"Shut up. If I remember correctly, I'm the officer. I command you. So eat if you don't want a fucking beating," Eren said in so much hostility while placing a hand on the heavy baton he had secured on his belt.

Levi's gaze glinted shock only for a moment before they turned hard. It was always the denial and embarrassed stage he received in the beginning whenever he followed his tactics. It was simple to him really. Harass all of his watchdogs (present and new ones) then drive them away each time.

But this young man in front of him was peculiar. Eren did not waver. Well, he stopped wavering. It was as if he transformed to a completely different person compared to the one he portrayed just a minute ago (naive). Now, Levi smelled trouble and stubborn. It seems this new boy will prove to be a challenge yet Levi decided that he was still willing to play.

The older man reached towards him, hands sliding down Eren's body almost touching, before he firmly gripped on the boy's crotch. Eren let out a surprise gasp. It was a miscalculation. He had stepped farther than he should have from the edge and near the criminal. Meaning Levi could touch him despite his chained state. Eren jerked back, shrinking into the bars and this time, Levi could only hover his hand. "Don't you want to be my toy? I can make you feel so good. Any time you want. Because if you didn't know—killing is not the only thing I'm good at."

Eren shoved him away, speed walked out of the cellar, and locking it to stand back on the other side of the bars. "Y-You need to hurry up and eat then take your medicine. The faster you follow my orders, the sooner we can both rest."

Levi eyed his body from top to bottom. "Will a lick in the neck and ear be enough to excite you? Or do you want me to go all the way to your dick."

Eren clenched his hands; thinking that the whole remark was ridiculous. "Just focus on your task, mister. I'm not interested."

"Maybe not yet, you aren't. You will be sooner than later if you keep denying me."

The time went by so slow and Eren was close to banging his head against the wall. Levi wouldn't stop verbally harassing him by making such crude (indecent) comments. So today was his first day and although he was happy to be working in the Scouting Legion, Eren could not help but think that he was assigned to the worst guy possible.

Oh, and remember the promise he made with Mikasa about reporting to her if he was ever touched by the man—Eren has decided to break that promise. Because there was no way in hell will he tell Mikasa that he has been harassed and groped by a shithole who he acknowledges secretly to have such a charming, rough voice.

February 27—

Report by Eren Jaeger. S-10 criminal, Levi, tended to his tasks. He ate lunch and dinner then properly took his medicine after. He sat and laid on his bed for the remaining of the day acting quiet and obedient. The night ends when head watcher, Alex, comes in to take over my place. Status of S-10: still imprisoned. Report Ends.