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The Lost Heir of Seiros

Summary:

Byleth’s unexciting (for her) life takes a turn when a car crashes near their home in the middle of the night. Before she knows what’s happening, she’s become a member of the Seiros Family, a crime syndicate controlling the city of Fodlan, and gets involved in the dangerous activities of the family.

(modern crime syndicate AU, eventual Dimileth, rated mature for violence)

Notes:

This idea was born from the different FE3H characters in suits images eisneRiegan showed me. My childhood friends 'encouraged' me to actually make my random mafia au idea into a multi-chaptered fic so here we are.

Some plot points are heavily influenced by the 4 routes so I'm tagging all routes spoilers to be sure. And I have no idea how to tag this. There will be fluff. There will be angst. There will be... my questionable humor most probably.

Chapter 1: Meeting at Twilight (MAIN)

Summary:

A crash wakes Byleth in the middle of the night. She never did like that apple tree anyway…

Chapter Text

Byleth was five years old when she first heard Sothis. She had been playing alone while her dad was on a job when Sothis first spoke. She taught Byleth proper tea etiquette and even slept next to Byleth. Her babysitter didn’t see her at all. When Byleth told her dad about Sothis, her dad’s eyes widened and he immediately talked to her babysitter about Byleth’s new friend. After that talk, her dad will simply listen to all the adventures she had with Sothis with a wistful smile. Byleth would later realize people thought Sothis was her imaginary friend. When she didn’t disappear even after Byleth had reached her sixteenth birthday, people would suggest to her dad that Sothis is a coping mechanism Byleth developed due to her isolated and sheltered upbringing. Byleth stopped talking about Sothis to other people not long after that but she knew that her dad knew that Sothis was still around, whispering in her ear and keeping her company whenever she was left to her own devices.

Byleth was eight years old when she first held a handgun. It was too big for her small hands and too heavy for her to use for a long period of time. It would be later that she realized that her dad had deliberately chose a handgun that would be difficult for a child her age to use at the time. Her dad had placed 2 cans and 3 bottles on the wooden fence behind their barn before giving her the gun. He patiently instructed her on how to safely handle the gun, how to aim and what to expect when she fire. They practiced until she could shoot all 5 objects in succession. Every weekend, her dad would give her a different firearm and they would practice until he was satisfied with her accuracy and handling of the firearm for the week.

Close quarter combat didn’t seriously start until she was thirteen years old. Before the rigorous CQC training, her dad would give her simple routines to keep her in shape, practice different scenarios which she needed to figure out how to get out, escape or incapacitate someone. One time, her dad had locked her in the trunk of the car and instructed her on how to escape from the outside. They practiced until she could do it without any prompting or reminders from her dad. 

They had to replace the tailgate of their car after that activity. 

Byleth was eighteen years old when her dad finally took her to one of his jobs. He let her prepare the sniper rifle, aim it at the middle-aged man walking with a younger woman in his arms, and pulled the trigger at her dad’s command. They left without a trace. 

She felt nothing about taking a life. 

It was a job. They were hired to kill a target. 

That was all. 

Sothis was obviously displeased of her lack of reaction over it but they didn’t talk about it and they didn’t acknowledge it. 

She would be twenty years old before her dad let her take down a mark on her own. She did everything perfectly. 

She always did everything perfectly.  

“Keep a low profile. Do not engage unless necessary. Always use a different name but never forget which name you have given. Never forget your contacts and always dye your hair.” 

She never understood the last two rules but she never asked. Sometimes, she would look at Sothis’ darker green hair and beautiful green eyes and feel a bit displeased by her dyed dark teal hair and blue contacts but she trusts her dad so she always remembered to abide by those rules. 

And that was how her life continued. 

Until one night when she woke up to the sound of tires screeching against the pavement. She heard a crash and she stood immediately, reaching for the pistol she keeps hidden underneath her pillow. 

Behind her, Sothis grumbled as she sleepily growled, “Ugh, I hope somebody is dead or dying. How dare they disturb our sleep.” 

She rolled her eyes at Sothis’ antics but kept quiet, walking towards her window. She kept the lights off, pressing her side against the wall next to the window as she lifted the curtain slowly. 

The porch lights and the headlights of a car was the only source of light outside. The black car had crashed on the large apple tree in front of their home. Three figures got out of the car, a young woman and two young men. They look like they were around the same age as Byleth but she couldn’t be sure. They were all wearing the same black suit and tie but each had a different shirt under the jacket. 

The young man with dark hair and a darker complexion compared to his companions laughed breathlessly before commenting as he pulled his tie and unbuttoning the first button of his yellow shirt, “Nice going, Dimitri, you just rammed our only way of escape to a tree.” 

The other young man with blond hair called Dimitri pressed a hand against his temple as he replied, “My apologies. One of the bullets seemed to have hit something and I lost control.” 

The only young woman with them sighed and patted her suit as she walked a few steps from the crash and Byleth wondered if her shirt was really blood red or if she was injured, “At the very least, it seems we are all alright. You are alright, correct? Dimitri? Claude?” 

Dimitri nodded as he replied, fixing the collar of his blue shirt, “I’m fine, Edelgard. Thank you for asking.” 

“Other than getting almost pancaked thanks to his princeliness? Yup. Still alright.” Claude replied with a hint of sarcasm lacing his tone. When he saw that Dimitri was frowning at him, he winked at him. Dimitri sighed and shook his head but didn’t say anything in his defense. Claude looked at the wreckage and asked almost like he was talking to himself, “Where did that bullet hit anyway? The break?”  

Byleth could hear the sounds of two speeding vehicles approaching their location. 

From the sounds of it, maybe 7 to 10 minutes before they get to their location?  

Both Dimitri and the young woman named Edelgard reached for the inside of their jacket, taking out a handgun. There wasn’t enough light for Byleth to identify what type of handgun they were holding but both of them held their respective firearm with the ease of a practiced individual. Claude walked towards the trunk of the crashed car and raised his arm just in time to catch something Dimitri threw at him. It turned out to be the car key that opened the trunk. Claude took out a violin case and opened it. 

Byleth immediately knew that it kept a disassembled sniper rifle. 

Her dad gave her a similar case for her sniper rifle.  

While Claude quickly assembled the sniper rifle, Dimitri briskly walked to Claude’s side. 

“Oh? He’s protecting him.” Sothis commented behind her and she nodded at Sothis’ observation. Dimitri was in front of the car, obscuring Claude from view, while Edelgard remained behind the car where she could easily take cover but have an unobstructed view of everything. She could easily provide cover fire from where she was. 

“We should take cover inside that house.” Edelgard suggested as Claude finished assembling his sniper rifle. 

“There could be someone inside!” Dimitri immediately argued, frowning at Edelgard. 

“There could be no one inside too.” Claude countered, hefting the sniper rifle over his shoulder as he continued, “I mean, think about it. No one has checked if we’re okay or anything. Don’t people usually see if anyone is alive when there’s a car crash?” 

Dimitri’s lips curved to a displeased frown but he remained quiet. 

“We have no choice, Dimitri.” Edelgard said in a cool collected manner. With a grim expression, Dimitri nodded. Edelgard nodded in acknowledgement as well and watched as Dimitri took point, walking briskly but cautiously towards the house. Edelgard and Claude followed him closely.  

Once Byleth knew that the three were walking towards their house, she quietly moved away from the window. She took the knife hidden under her bed and walked out of her bedroom. She opened her door slowly, making sure to keep it from squeaking like normal. She only opened the door enough for her to slip pass thru, keeping her handgun in front of her but aimed low, resting the butt of her handgun against the back of the hand holding the knife. There was no light coming from the crack of her dad’s bedroom door and she briefly wondered if he went out without informing her after she went to sleep. She descended the stairs, skipping the creaky fifth step and aimed her handgun at the front door just in time to see it open. 

“Don’t move.” Her dad’s gruff voice commanded from the shadows next to the door, his shotgun aimed right at Dimitri’s chest. 

Byleth quietly ascended the stairs once more, aiming her handgun at Dimitri’s right leg. Skipping the creaky fifth step and stopping on the top of the stairs, she watched as Dimitri stared at her dad. 

“No one inside, was it, Claude?” Dimitri deadpanned before he gave a sigh that sounded like a man who was used to being aimed at. 

“I didn’t say no one was inside.” Claude defended in an almost carefree manner, “I said ‘could be’. Big difference.” 

“We mean no harm. We simply need a place to hide.” Edelgard stated, trying to salvage the situation, “We are being pursued and they will be here soon. Believe me, they will not hesitate to kill you as well.” 

“Slowly get inside with your hands where I can see them.” Her dad ordered as he turned on the lights, keeping his shotgun aimed at Dimitri as he entered the house with his hands up, holding his handgun with his right hand but keeping his index finger away from the trigger. Edelgard and Claude entered cautiously as well with their hands up. Claude kept his sniper rifle against his right shoulder while Edelgard’s handgun was nowhere to be seen. All three kept their eyes on her dad, oblivious to Byleth. Dimitri slowly moved so he was covering Edelgard but her dad aimed his shotgun at Dimitri’s chest, “Don’t move, kid.” 

Dimitri stopped but didn’t return to his previous position, protecting at least half of Edelgard’s smaller figure. 

Byleth aimed her handgun at Edelgard. The blond may be protecting his companion from her dad’s shotgun but Byleth has a clear shot if the need arises. A few seconds passed by with the only sound coming from the approaching mysterious vehicles and Byleth watched as her dad stared at the three. 

“Shit.” Her dad cursed and lowered his shotgun. He rubbed his face and cursed, “Fuck. You’re from the Seiros Family.” 

“Oh? You know us?” Claude asked in a carefree manner while Edelgard and Dimitri looked surprised.  

Edelgard quickly returned to a blank expression while Dimitri opened his mouth but her dad cut him whatever he was about to say with a frustrated growl, “I don’t know either of you kids but this blondie looks exactly like Lambert when he was the same age. Jesus fuck.” 

“You knew my father?” Dimitri’s voice cracked as he asked, his eyes wide. 

Her dad raised his shotgun at the three once more and growled, “Did Rhea sent you? Does she know we’re here?” 

“Woah, woah. Let’s all calm down, okay?” Claude interrupted, taking a step away from Dimitri and Edelgard, “Lady Rhea didn’t send us. We don’t even know who you are or whatever you are to the main branch. Our car was shot at and we tried to escape but our car crashed… thanks to his princeliness over here.” 

Dimitri's shoulders dropped a bit, obviously due to Claude's additional comment, but he remained silent. 

“Claude is right. We have no business with you nor do we care about your relationship with the main branch. We simply wanted-” 

Whatever Edelgard was about to say was cut off by the skidding of two cars to a stop. They all turned towards the door and her dad immediately closed it.  

Her dad pressed his back against the wall next to the door while Dimitri took the other wall, holding his handgun with both hands but he kept his index finger away from the trigger. Edelgard crouched behind the sofa, her handgun immediately aimed at the door while Claude ran towards the stairs, stopping when he finally noticed Byleth who was now aiming her handgun at his chest. Claude blinked before cheerfully greeting, “Oh, hello there.” 

Both Edelgard and Dimitri turned towards Claude and were surprised by the silent woman on top of the stairs.  

“Byleth, trade.” Her dad ordered and Byleth immediately walked pass Claude towards her dad.  

Claude pressed his back against the wall so Byleth could pass, turning his head upwards as he commented, “Nice dress, by the way.” 

Dimitri’s cheeks reddened as he sputtered, “Claude!” 

Claude simply grinned at her dad’s glare while she blinked at Claude, not sure what he meant by that. 

Sothis groaned as she reminded her, “We forgot to take a robe.” 

Oh. Right. 

She was wearing a nightgown, one of her shorter black ones that ends by her thigh with lace covering her chest which she picked because it was a hot night when she went to sleep. Her dad simply sighed and threw his shotgun at her. She threw her handgun at him and caught the shotgun.  

“They’re not in the car!” 

“Check the house!” 

Her dad quietly walked towards the kitchen as he ordered, “Sniper on top. There’s a window on the second floor overlooking the front of the house. Target everyone still outside once they start entering. Blaiddyd kid and red girl, stay behind the couch, do not fire until my daughter says so. Byleth.” 

“First strike.” Byleth said and her dad nodded. Claude had already disappeared to the second floor. 

“I’ll circle around back and take out anyone coming from behind us.” Her dad finished before walking briskly towards the kitchen. Dimitri walked towards the couch but stopped in front of Byleth. Looking at the floor, he took off his jacket and offered it to Byleth. 

Byleth blinked at him, staring at the shoulder gun holster he was wearing. Byleth didn’t realize he had another gun hidden under that suit jacket. 

Sothis cleared her throat before ordering, “Well? Take the jacket and say ‘thank you’. Give the poor boy a break. He looks ready to burst.” 

Byleth noticed Dimitri’s ears had turned red just as his face but did not comment on it even when Sothis was cooing at how adorable it was in her usual condescending way. She took the jacket and placed it on her shoulder as she said, “Thank you.” 

“We’re terribly sorry for barging-” 

The sound of the door knob turning stopped Dimitri’s words and he nodded at Byleth grimly before he quickly rushed towards the sofa, crouching next to Edelgard.   

The door opened and everyone held their breath. Once Byleth saw the foot of a man entered their home, Byleth stabbed her knife at the foot, crouching as she impaled the man in front of her.  

The man screamed and Byleth pressed the shotgun right at his chest, firing at point blank range. The impact tore through the man’s chest, scattering the buckshot on the men behind him. She heard two other men scream as she quickly reloaded the shotgun. As the first man fell, she aimed the shotgun and immediately fired at the nearest man, taking half his head off. Taking advantage of the men’s surprise, she quickly fired two more shots, taking three men down, before quickly ducking at the wall next to the door.  

“Six.” She whispered to herself. 

A second later and the men outside began shouting.  

She could hear the sound of a sniper rifle firing and a body falling.  

“Five.” She corrected, turning towards the two behind the couch, “Get ready, aim at the door. Shoot on my mark.” 

She didn’t wait for them to acknowledge her order, aiming the shotgun on the ground and  lowering her body until her knees were pressed against the floor. 

She listened at the incoming footstep, calculating the distance just like her dad taught her then finally, “Now!” 

She immediately heard a shot, hitting the man who was just a foot away from the home on the chest.  

“Four.” She counted. 

She heard another shot a second later, too early for a second shot. 

Only one of them shot immediately. 

That was fine. 

She already knew what she would do if no one listened to her in the first place.  

She used the shots’ momentum to kick the man off, shooting at the door while maintaining her cover. She managed to clip another man on the shoulder who howled in painful rage. He took a few steps back and Claude finished the job. 

“Three.”

The remaining three men were better prepared and pulled their triggers as they rushed to the door, out of Claude’s range. Byleth rolled away from the barrage of fire while Dimitri and Edelgard provided cover fire from the sofa. One of the men was shot in the head by Edelgard with two well placed shots. 

One of the men rushed towards her, grabbing her by the ankle. The jacket fell from her shoulders as they struggle with the man on top of her managing to grab the shotgun. She stabbed him on the thigh at the same time his head jerked to the side, blood splattering her face. 

She turned towards the couch in time to see Dimitri running towards her as he fired three more shots at the man on top of her, two to the chest and one right in the middle of the neck. She stared at him as he grabbed the corpse by the neck and threw it off of her before asking her, “Are you alright?” 

She was about to reply when she heard Sothis shout, “The girl!” 

She acted on instinct, barely realizing that the last man was aiming his gun at Edelgard who was in the middle of reloading. She leaned on Dimitri, her chest pressed against his front, taking the spare handgun from his shoulder holster and aimed it at the remaining target. There was no time to aim properly. 

She let her instinct take over. 

“If you’re aiming to hurt or you have no time to aim, go for the chest. It’s a large target, easy to hit and the impact will be enough to buy you more time.” 

Her shot hit him on the shoulder, his gun going off and missing Edelgard’s head by an inch. The man screamed in rage and Edelgard fired two shots. One shot hit him right in his right eye while the other shot hit him below the nose. 

The last man fell with a thud. All three of them were breathing hard, adrenaline coursing through their veins. She moved away from Dimitri, returning his spare handgun to his holster as their eyes meet.

Then she heard more shots coming from behind the house. She immediately grabbed the discarded shotgun as she said, “Dad.” 

That one word broke whatever spell Dimitri was caught on and he immediately ran after her as she rushed outside. Edelgard followed the two of them as well. 

When they got outside, her dad was firing at a car driving away. One of his shots pierced the back window and they all watch as the car swerved violently. Her dad wasted no time, firing at the tires this time and the car tumbled, flying into the air for a second before smacking back into the ground with the hood of the car smashing into the pavement. 

“Holy shit.” Claude exclaimed, catching up to them in time to see the fate of the car, “Did that really just happened?” 

“I… I think so.” Edelgard replied, too dumbstrucked by what she saw. 

Claude threw Dimitri’s jacket at him which he had grabbed on his way out as he tried to get a closer look at the car. Dimitri caught it on reflex, still staring at the upside down car.  

Just… who the hell are these two? 

Byleth didn’t look fazed at all, walking towards her dad. Her dad turned towards her and asked, “You okay?” 

Byleth nodded and her dad frowned, wiping the blood on her cheek. Knowing her dad, she informed him immediately, “Not mine.” 

“That’s good.” Her dad nodded at her before turning towards the three dumbstruck trespassers. Byleth tilted her head when she noticed that Claude wasn’t dumbstruck at all. Instead, he was looking at her dad (or was he looking at her?) with a smile on his face but with eyes gleaming with…  

Interest? 

“That boy… is definitely strange.” Sothis whispered, “He looks like he wants to interrogate us. Or worse… dissect us.” 

Byleth wanted to roll her eyes at Sothis’ over the top imagination but… she did have a point. Byleth had spent her entire life being alert and trusting her instincts haven’t failed her yet.  

“Now then, let’s get back to business, shall we?” Her dad aimed his gun at Dimitri who was in the middle and in front of the two, forcing Byleth’s attention back at him. 

“What?! No!” Sothis cried out, “Stop this madness!” 

Byleth stepped in front of Dimitri, right in front of her dad’s gun, to the surprise of everyone. 

“Byleth, step aside.” 

“No.” Byleth replied in an emotionless tone, echoing Sothis’ hissing “No”. 

“He saved my life.” Byleth informed her dad, making him sigh. 

“Of course he did. He’s part of the Faerghus branch. Hell, he’s a fucking Blaiddyd. That’s what they do.” He rolled his eyes as he continued, “You order them to jump, they do fucking somersaults.” 

Before anyone else could comment, a motorcycle rushed between them, heading straight to Byleth. Dimitri moved to grab Byleth but Byleth stepped back at the same time, dodging the incoming motorcycle. They collided, making Byleth lose her balance and Dimitri grabbed her by the shoulders, keeping her upright. 

Her dad cursed, berating himself for being to focused on the three brats and his daughter’s impulsive action to hear the motorcycle before it was too late. 

No. 

The motorcycle was quiet the entire ride. 

Just like the two cars driving towards them, boxing them against their house. 

The driver of the motorcycle stopped in front of Edelgard and Claude and the driver placed one of her feet on the floor as she aimed an Uzi right at him. 

The doors of the two cars open as a loud booming voice stated, “Nobody moves! You’ll all regret the day you decided to go against the Seiros Fami- Is that?! Jeralt?!” 

Her dad groaned, rubbing the bridge of his nose as he lowered his other arm, “Why did it have to be him?” 

“It’s me! Alois!” The suddenly cheerful man dressed in the same suit as the three but with a white shirt underneath walked towards her dad and wrapped him in a bear hug, “You’re alive!” 

Noticing that Alois knew the man who had been aiming his gun at Dimitri and was now talking to him like they were old friends, the driver on the motorcycle holstered the Uzi and turned off the engine of the motorcycle. The driver took the helmet off before turning towards Claude and Edelgard as she asked, “You two alright?” 

“Oh, it was just getting good. But I got to say, you guys have impeccable timing.” Claude sighed with a smile, making Edelgard roll her eyes at Claude’s theatrics. 

“We’re all alright. Thank you for asking, Shamir.” Edelgard replied. 

“I’m sure his princeliness is more than okay though.” Claude jokingly commented and both women turned their attention towards their companion who was near enough for them to hear their conversation. 

Byleth had already regained her balance and nodded at Dimitri as she said, “Thank you.” 

“No, it should be me that should say thank you.” Dimitri stopped, realizing she was still just clad in a short nightgown, and wrapped his jacket around her. He kept his eyes trained to her face as he continued, “You helped us even after knowing who we were. Not many people would do such a thing.” 

“Who you are?” She repeated, tilting her head slightly. 

“The Seiros Family.” Sothis reminded her with a resigned sigh. 

“Oh, yes. The Seiros Family.” Byleth repeated. 

Dimitri’s lips curled into a chagrined smile as he nodded, “Yes. The Seiros Family…” 

“To be more exact, we’re part of their branch families.” Claude clarified as he and the two women walked towards Byleth and Dimitri. 

“Please forgive our late introduction.” Edelgard placed her hand on her chest as she introduced herself, “I am Edelgard von Hresvelg and I am the current heir of the Adrestia branch family.”  

“Ah, yes.” Dimitri bowed slightly as he introduced himself, “And I am Dimitri Alexandre Blaiddyd from the Faerghus branch family. As your father have deduced, my late father was the previous head of our branch family and I… Well, my uncle is the current head of the Faerghus branch.” 

“Name’s Claude von Riegan of the Leicester branch. Riegan is the leader of the Leicester branch so I guess you can say I’m heir to the Leicester branch too.” Claude took off his jacket and draped it over his left shoulder while he had his sniper rifle leaning against his right side. 

Byleth only knew the Seiros family by reputation. Her dad refused to do any work for them but made sure Byleth knew enough so she can steer clear of them if needed. Hell, he only took jobs set in Fodlan when there was no other choice. 

The Seiros family was a crime syndicate family that controlled Fodlan city in the shadows. Other than the elusive main branch, the syndicate have 3 well known branches.  

Adrestia branch family is the branch that controls all legal activities of the Seiros family. Adrestia branch family is also the most well known of the branch family and it is rumored they have connections to both the political and the entertainment world. Faerghus branch family is the branch that makes sure all other activities of the Seiros family are running smoothly. Faerghus branch family is the sword and shield of the Seiros family and well known to be loyal to the main family with rumors suggesting that their loyalty reaches fanaticism. The Leicester branch family is the branch that does everything and anything for the main branch. They are comprised of different factions that formed an alliance to become as big as the other two branches and, as such, their specialties and job description differ from faction to faction. 

Byleth glanced at her dad and saw him staring at her grimly as he and the man named Alois walked towards them. Byleth returned her attention towards the three, noticing that the motorcycle woman didn’t introduce herself. 

“Rude.” Sothis harrumphed. 

“Can we get the name of the lovely badass who saved us?” Claude grinned as he added, “Asking for my good friend Dimitri here, of course.” 

“Claude!” 

That finally got Byleth’s attention. The three heirs seemed to be waiting for her to introduce herself, the two young men more so than Edelgard it seems, so she said, “I’m-” 

“Lady Sothis?!” Alois’ interruption stopped her words and everyone turned towards Alois. Dimitri and Edelgard looked like someone had said they were talking to a ghost while Claude looked like his Christmas gift came in early. 

“Wait! What?!” Sothis shouted, mirroring Byleth’s feelings, “How does he know my name?!”