25/10/2018: I had no idea I forgot to change over this fanfiction from a reader insert version on another website, to an OC on this website - I copied and pasted it all over at like 3:00 AM for my time. Apologies everyone!

Thanks to the guest for pointing that out Erwin and Bláithín were roaming the underground because there was word of some trouble that had been bubbling away in the Underground District. Plus, this trouble was going to be her squad, whether she liked it or not. She was going to give them the benefit of the doubt though - maybe a trio of thugs would treat her nicely?

Pretty unlikely, though.

She and Erwin walked down the alleyway that descended into the stairwell. Bláithín hadn't forgotten what it was like down here when she fled here with no where else to go. Her eyebrows furrowed at the sight.

People down here suffered so much, and lack of sunlight was a major problem based on what she had heard from up above. Eventually their bones would weaken over time and would no longer be able to walk. Citizens down here sat down constantly when their legs wouldn't let them get up anymore.

It stunk like a cistern down there due to people dumping waste wherever. There were mini stalactites hanging from the top and there were little holes on the surface that let the dim rays of sunlight shine down. The houses down here were nothing more than mud houses with windows carved into them.

Down here, it was disgusting, rotten and utterly vile. Nothing good ever came out of it. It wasn't a sight for the squeamish to behold. People's bodies lay about unclaimed for days on end, waiting for Death to come and put an end to their misery.

In the corner were people gambling for money, alcohol and drugs. They all had to be drunk on something to survive down here, but then again, all humans latched onto something to survive in a world where despair was bountiful. Similar to outside of the Walls, the Underground was an absolute and perfect example of 'survival of the fittest.'

"It's so horrible down here, I don't think you could ever get used to it." She said to him. The two Squad Leaders continued to walk through the Underground, when there was a bit of commotion to be heard up ahead amongst the looming criminals. They both looked at each other and started to adjust their gear. They ran up and pushed the citizens that started making a crowd aside. Ogling wasn't going to make the commotion die down.

Based on what she just saw, the group of thugs they were after had bust through a stack of crates holding possessions that may have been smuggled down from above. With the crates broken, their contents spilled out onto the ground which opened the opportunity for other mercenaries to steal. Once the crates had been knocked over, a thug that was short in height bashed into a merchant before propelling himself into the air again.

"AUGH! THAT HURT! OWW! OWW! Oi! Hold it right there!" someone exclaimed.

Bláithín heaved a sigh. I guess that's our cue, she said to herself. She reluctantly picked up her pace once told to by the blond male beside her. Erwin and herself shot their grappling hooks into the air and followed the trio at a leisurely pace. The MPs hovered in front of them too but Erwin, and [F/n] were called in to subdue them and capture.

"OI! YOU! SHORTY OVER THERE! AREN'T YOU GOING TO EXCUSE YOURSELF AFTER BUMPING INTO ME?!" the man continued. "ARE YOU DEAF, SHORTY!?"

"You guys better stop, they're-," a man tried to reason but got thwarted.

"Hey! Are you askin' for a hole in yer head?!" the man threatened.

The squabbling continued. This is something that happened on a regular basis. The short man, around 5'3 stopped dead in his tracks and reached inside his pocket and everything fell quiet and you could hear the short man's friends talking.

"We don't have time for this bullcrap," said the brown haired man.

"Well...but isn't this perfect timing for a warm-up before training?" the red haired lady asked.

Suddenly, there was a click.

The short man or their leader sharply pivoted around and took out his gun and fired. There was a small breeze which blew up the man's poncho and to Bláithín's surprise, he was wearing a 3DMG. Just where did he get his hands on that? The bullet flew as fast as lightning, and was millimeters away from the grazing the man's head.

Instead, it crashed into some barrels that were containing some fluids, possible the limited supply of clean water.

The leader of the group went to go in and kill the man who ticked him off by attempting to pierce him with his grappling hooks.

"SHIT!"

His opponent went to shoot with his gun, when the man ascended into the air with his 3DMG and landed, stomping on one of the man's friends hard into his gut. The man he took down just there was bald and was very imposing in height, possible taller than 6'2 Erwin.

"Oi...Next is the giant," Levi breathed.

"Heh, heh! That was a waste of time. I'm taking the high route," the red haired lady, Isabel, stated.

Erwin glanced up at the short man, who had raven black hair and whose bangs hanging over his temples. It was almost as if his gaze was enough to make him stop mid-air. The raven haired man looked back at Erwin and noticed the Wings of Liberty insignia on his breast pocket and just one word crossed his mind: 'Shit'. Erwin held some ambitious and determined smile about him.

Erwin and Bláithín began to follow the trio as they created quite a ruckus amongst the civilians of the Underground District, zipping in and through them on their 3D Manoeuvre Gear.

"You damn thugs!" an old man cried after being knocked over.

Erwin and Bláithín were around twenty metres behind them, continuing to pursue them as fast as they could. Given that they weren't so far away, the veteran scouts could hear everything they were saying. The short, jet black-haired man suddenly took a sharp turn mid-air before piercing the pillar of a jagged wall with his grappling hook. Just enough time for Erwin and Bláithín to get the upper hand and catch up with them. The red haired lady looked back with a wide grin, making her teeth visible before letting out a whistle.

"THEY AIN'T HALF BAD!" she chimed. The short man scowled at her sudden cheerful outburst.

"That's the Recon Corps for you," said the leader of their group.

"The Recon Corps? Are you certain!?" replied his other brown haired friend.

"I saw the crest on their backs as I was passing by. It was The Wings of Freedom," he replied.

"The Recon Corps are those guys who go outside the walls and actually fight titans, right? Wow, I guess guys who've been trained with experience with actual combat are a whole other deal, huh, Levi?" his male friend replied.

Levi... Huh, Bláithín noted to herself.

"I have no intention of getting involved with them. But now that it's come to this, it won't be easy to shake them off," Levi stated.

"I won't lose! I'll make every damn one of 'em cry!" the red-haired lady piped, presumptuously.

Levi said something that wasn't completely audible so the red-haired lady said it out loud. "As long as we don't get captured!"

"If you say so."

"You guys know what to do, right?" Levi asked.

"Yeps!" replied the girl.

"Sure, whatever," came the other male's voice.

And with that, the three zipped off in different directions. Bláithín and Erwin both heaved audible sighs of annoyance and frustration.

"Alright, I'm taking the black haired man. I know you're more than capable of handling the other two. The leader's intriguing, I'll go after him." Erwin told her.

"Sure." She said back to him. Bláithín decided to go after the girl first.

"You can't catch me!" she boasted.

The girl zipped around a huge stalactite and once around, she launched her grappling hooks in Bláithín's direction. This was a huge opportunity but dangerous at the same time. As the hook flew through the air, about to impale her, she simply hovered in the same place and used her reflexes and caught her rope and pulled her back forcefully. As far as people her age went, she was as light as a feather, and took little or no effort to pull her back. As she hovered, the girl scowled up at her like a defeatist. "I just did." She whispered to her.

"Bitch..! Let me go, now!" she screamed.

"ISABEL!" her male friend shouted. Being the noble person he must be, he immediately zipped back to the sound of her voice. "Aw, crap! Isabel!" he whined.

"It's not my fault, Farlan, they're actually kind of good..." she replied.

Bláithín took a pensive moment, eyeing the two people before her. "Come here." She ordered. Farlan shamefully zipped over to her, his head hung low. She grabbed his arm, and Isabel's rope, and gently landed, to avoid extra grief.

"Show me your hands," she ordered to the brown haired male. Farlan laid his hands out, keeping them there, while she tied Isabel's rope to her belt, earning an annoyed from her. She handcuffed his hands, only realizing one finished that she only had one pair. "Right..." she sighed. She undid Isabel's rope from her belt, still holding it, and swung her over her shoulder, and kicked Farlan forward to the commotion being created by Levi's confrontation with Erwin and Mike.

After a few moments of walking later, she came across Levi and Erwin approaching him. She arrived at the point where Levi leaned in to throw a powerful fist at Erwin. Erwin gritted his teeth in frustration. Erwin kicked Levi away from him.

"STOP!" Erwin shouted upon noticed Bláithín had arrived. "Take a good look around you!" he told him.

Levi's rage momentarily subsided when he saw Bláithín kicking Farlan forward and Isabel swung over her shoulder. His gaze softened upon seeing the female veteran come closer; he recognized her instantly. She had grown since then, if he had to estimate she was now a good three inches taller than him and he could tell she had grown into a formidable soldier.

Whether he wanted to admit it to her or not, he felt sorry for her that day. He never held much regard for the greedy pigs that lived in the interior but he knew by her face that day - the day he left her in another soldier's care before he took her to the military base - that she had been stripped of everything she had ever had.

He wasn't going to show much sympathy to her now though - just look at what she managed to accomplish? Within minutes, she subdued his companions and had them at her mercy. She could have done anything she wanted to them - beat them, kick them or whatever else - but he could tell that it probably wasn't within her nature.

"Lemme go! You little-!" Isabel piped, squirming about like a bag of worms, but Bláithín cut across her.

"Erwin, are you alright?" Bláithín asked him.

"Don't waste all your energy, Isabel." Farlan told her.

Bláithín walked over and forced Farlan to kneel, and let go of her grip on Isabel. She walked over in Erwin's direction when she noticed Levi had given her one of the foulest glares ever imaginable.

"I'm fine. Good work in capturing them both," Erwin replied and averted his eyes to Levi. "I'm going to ask you a few questions. First, where did you obtain these?" he asked him, referring to the 3DMG.

"..."

"..."

"Your 3D Manoeuver Gear skills are also remarkable. Where did you learn how to do that?" he asked them.

"..."

"..."

Erwin stepped closer to Levi. "You're the leader of this group, correct? Have you ever received military training?" he asked him. Levi looked right into his deep sea blue eyes with his steel blue ones. His eyebrows were furrowed and had also glared at him, but for some odd reason, it was not nearly as bad as Bláithín's. "Your face is telling me that you're plotting how to best kill us and escape, right?". He paused and glance over at Bláithín. He clicked his tongue and scoffed.

"If possible I didn't want to be too rough, but..." he began to say before motioning over to his colleague. Bláithín nodded and obeyed - Erwin was next in line to be commander as she had predicted years before, she was to do what he was told. Obeying orders is good, she always told herself. She walked up close to Levi and ruffled his hair, and Levi gritted his teeth out of pure hatred, before shoving him into a filthy puddle.

Levi was quite mistaken. There was no hesitation in her moves at all and he had to admit he didn't expect the sharp pain to come from his neck.

"Guh-!" came Levi's response. "You fucking bitch…" he growled, seething. His eyes were burning with rage as he glared back at her, spitting out the dirty water from his mouth.

"Let me ask you one more time..." Erwin began. "Where did you learn 3D Manoeuvers?"

Bláithín turned his head up to face him, but not too roughly, so his complete attention was on Erwin.. The two stared deeply into each other's eyes, Levi waiting to be let go of and Erwin waiting for an answer.

"We didn't learn from anyone! Get off your high horse, mister public servant!" Isabel yelled in his defence.

"We picked up these skills in order to survive this dump. Someone like you - who doesn't know the taste of sewer water - wouldn't understand!" Farlan added.

"My name is Erwin Smith", he stated, "what is yours?"

"..."

"Hey now, listen. We certainly don't have the time to play games. I'm telling you now you don't stand a chance against us two." Bláithín warned, and shoved his face into the puddle once again. She grabbed him by the hair after a few moments of him taking in the bacteria of sewage and sludge that the puddle had to offer. She could tell that he was probably equally as angry as getting dirtied as he was getting caught. He inhaled sharply.

"Ugh..!" he wheezed,

"I admire your spirit, but if you keep this up we'll have to get your comrades involved." Erwin warned.

Bláithín stepped back from Levi and to the two friends of his, and turned them to face a pipe that had sewer water gushing out of it.

"IF YOU'RE GOING TO DO IT, JUST DO IT ALREADY!" Isabel shouted.

Now it was Erwin's turn to grab him by the hair. He knelt down before him, "My name is Erwin Smith."

"You bastard..." Levi hissed, spitefully. Dirty sewer water dripped down his face. His teeth were gnashed together in spite and utter rage.

"Your name?" Erwin questioned.

"...It's Levi," he told him through his gritted teeth.

Erwin knelt down in the puddle to get a better look of him. "Levi. Won't you strike a deal with me?"

"A deal...?"

"I won't ask what crimes you've committed. In return, you'll lend me your strength. Join the Recon

Corps." He told him.

"And if I refuse?"

"I'll leave you under the Military Police's responsibility. In the first place, considering all the crimes on your record, you getting off easy is out of question. However, your friends won't be able to hope for decent treatment, either. Choose whichever you'll prefer." He told him.

Levi glanced over at his friend Farlan, whose neck could be slit with Bláithín's blade at any moment. He looked up at Bláithín for a few seconds, and once gritting his teeth and hissing a sigh at her, he turned back.

"I'll take it. I'll join the Recon Corps." He said.

Levi Ackerman, Farlan Church and Isabel Magnolia were eventually taken inside, once the soldier gave word to the Commander that Erwin and Bláithín had arrived back with the thugs. They were taken to a spare room.

Bláithín was the first person to be asked to go in and greet them. It was the right thing to do, after all, she wanted them to be comfortable around her. Of course, it would take a lot of effort to have any good relationship with them. It was an arduous and seemingly impossible task to try bond with them, similar to that of dragging blood from a stone.

The stiff knob twisted clockwise and the door swung open making a slam. Isabel and Farlan looked up to see it was her: the soldier who practically submerged Levi's head into the puddle and threatened them to drink sewer waters.

"Hey." She said simply.

"Ah-!" Isabel piped, standing up abruptly and immediately getting into a fighting stance.

"Isabel, there's no need for that." Bláithín said to her.

"Isabel, sit down." Farlan told her.

"It's not my fault the mad woman is here!"

The blonde pretended she never heard that. "Uh, yeah, hi. My name is Bláithín Hahn and I'm a squad leader here. I've been told that I'm getting a squad, which is going to consist of you three.. You'll be getting your uniforms soon." She said simply.

There were three cups of tea on the small table in the middle of the room. Levi happened to be drinking from one of them. Bláithín corked a brow upon noticing Levi's method of drinking it. He didn't hold it by the handle, instead his entire hand circled it and had a tiger's claw like grip as he slurped from it. He noticed she was looking at her.

"Tch, what the hell is it you want?" he spat.

Bláithín sighed. "There's no need to talk to me like that," she lectured, trying to remain as patient as ever. "Keep it up and I'll have you clean out all of the women's rag bins."

Levi quickly leaned back and averted her eyes, saying nothing more; cleaning up women's menstrual rags was not something he fancied doing after just arriving.

"Oh, Isabel? I forgot to mention. You're wanted. I have no idea why, though." She stated. Bláithín gestured towards the door, indicating whoever wanted her was waiting outside.

"Mm-kay," she chirped, merrily.

Bláithín and Isabel left the room.

What have I gotten myself into, she asked herself.

Please review, I'd love to hear your thoughts! We'll be having more Levi-centric chapters before the expedition!