A/N: Yay, another fic for my Bad Things Happen Bingo! I'm on a roll! This is also my very first FE3H fic. I LOVE the game and it's about time to write something for such an amazing game.

This fic was inspired by AnimeSmash's Ferdibert fics. I plan on writing a Ferdibert fic myself sometime soon as well so keep an eye out!

Anyway, for my Bad Things Happen Bingo, here's Promises!

ENJOY!

We have your professor, Emperor Edelgard. If you wish to see him again, head to Grondor Field within two days. Alone. Bring help, and we'll deliver him piece by piece at your doorstep.

She should have known. With Those Who Slither In The Dark still at large, she should have seen this coming.

TWSITD were a ruthless bunch, but she had no choice but to ally with them. Once she had reached her goals, they must be killed lest they would cause chaos and undo everything she had worked hard for.

She should have realized that it would put her loved ones in danger. Including Byleth, her beloved husband and professor.

Of course they would go after Byleth. He was her pillar, her support when she had gone too far. It made sense that TWSITD would take him. Even though Byleth was strong, TWSITD was just as, if not more, powerful, and they were likely able to take him down by outnumbering him.

She had already lost her Byleth once seven years ago. She wouldn't let that happen again.

It took more time than necessary to leave the monastery without anyone noticing. Especially Hubert. Hubert insisted on accompanying her to rescue Byleth, as she expected. She knew better than to give him an order he wouldn't agree with, as he would completely ignore it if it benefits Edelgard.

Miraculously, after a few hours, she had avoided everyone when she snuck out. With determination to rescue Byleth, she was off to Grondor Field.

Grondor Field was surprisingly the same as it was seven years ago. The lush grass and trees and the empty ruins were untouched, as if no battles to the death had happened here. Any blood that stained the beautiful scenery had since been washed away due to rain. Despite how beautiful the scenery was, the area had a sense of dread surrounding it. TWSITD were nearby, and she could feel it.

Edelgard stepped up one of the many hills, her eyes glancing around for an ambush and for Byleth. Her grip was tight around her axe, raised and ready to strike down anyone who opposed her. Based on the ransom note's demands to have her come alone, this was definitely a trap. But Edelgard couldn't leave Byleth in the hands of them. He had saved her life seven years ago from Kostas and his bandits; it was time to return the favor.

She continued forward, her eyes shifting around for any enemies hiding to ambush her.

When she reached the top, any and all caution was thrown out the window upon seeing a horrifying sight. She nearly dropped her axe and her mouth was opened in horror as she stared at what—or rather who—was in front of her.

Byleth stood there, thoroughly bound to a tree with chains. Blood seeped down from his wounds, staining the steel chains holding him in place red. His left eye was swollen shut, and there was a large gash across his chest. The chains dug into his wounds, causing him to groan in pain.

"Byleth," Edelgard gasped. Without another thought, she rushed towards her professor. She touched Byleth's cheek, stroking it gently. She felt the man shivering, as if he was freezing.

His good eye was half lidded, as if he was struggling to stay awake. His breathing grew quicker upon hearing his wife's voice.

"E-El…" Byleth groaned, his voice cracking as he said Edelgard's pet name. Edelgard gritted her teeth—he was undoubtedly terrified.

"I'm here, love," Edelgard spoke in a soft voice. Using her axe, she began sawing through the chains holding her husband to the damned tree. "You're safe now…"

Byleth shook his head, but groaned in pain when nausea hit. He didn't resist Edelgard from freeing him—the pain was unbearable for him. His good eye was locked in the distance, and his breathing quickened.

"N-no," Byleth whispered. "It's… a trap… run…"

"I know," Edelgard acknowledged. "But leaving you here is not an op—"

"Edelgard!"

Byleth's scream caught her off guard. She turned, but it was too late—a Thoron spell shot towards her, shocking her and paralyzing her. Electricity crackled around her body as she went on her knees. She gritted her teeth, fighting the urge to cry out in pain.

"El!" Byleth screamed, his good eye wide and his heart beating wildly against his chest. Despite his pain, he struggled against his bonds in order to reach Edelgard. No. Edelgard should have ran. She should have been safe. But now TWSITD had her in their grasp.

"Welcome, Emperor Edelgard," a deep, sinister voice greeted in a taunting manner.

Edelgard glanced up, seeing a familiar cloaked figure and his men approaching the helpless couple. One of his companions' hands were crackling with electricity—they were the one to use Thoron on Edelgard. Thales.

She attempted to get up, but the electricity around her body crackled, and she grunted in pain. She went back down on her knees, her glare fierce towards Thales in an attempt to appear defiant. But deep inside, she was afraid. Afraid of what Thales would do to her and to Byleth. Byleth only watched as his wife struggled to stand to no avail, guilt filling his eyes and his heart breaking in two.

"I figured you would be behind this, Thales," Edelgard spoke. "I'm here like you wanted. Let Byleth go now." Her glare grew stronger, not wanting to show Thales that in reality, she was scared. She wasn't going to go down that easily.

Thales shook his head, a sinister smirk on his face. Seeing his victory smirk made Edelgard shiver. "Now why would I do that?" He approached Byleth, stroking the professor's cheek. Byleth shivered, trying to back away, but thanks to being chained up, he was unable to. "He's a good test subject, isn't he?"

"Don't!" Edelgard cried out, before she lunged. However, the electricity held her down, before she grunted in pain and returned to her knees.

"El," Byleth warned. "Don't push yourself. It's…" He sighed, looking away from his wife's concerned gaze. "Hopeless."

Hearing that last word coming out of Byleth's mouth broke her heart. Byleth never gave up like that. Even when he was up against Rhea in their final battle against the church. Even when he had to fight Edelgard herself when she revealed her true intentions. Byleth would never quit, even when things appeared to be hopeless.

"That is right," Thales agreed. Turning to Edelgard, he raised a hand. A spell bubbled in his hand—a Death Γ spell, specifically—ready to strike her down. "Give up, El. It's no use to fight back."

Before Edelgard could even react, the spell hit her squarely in the chest, and everything went black. The only thing she heard was Byleth's panicked cry of "EL!"

She thought she was dead. She really did. But when consciousness began to return to her, she realized that the spell merely knocked her out.

When she was able to open her eyes, she could see large stone walls surrounding her. Further in the room stood a door with small jail bars in front of its small window. Chains hung on the walls, some of them containing skeletons of long dead prisoners.

It took her a moment that she too was chained to the wall.

Her heart skipped a beat, and panic began to set in. Not again. Oh no, please no. Her breath quickened, sweat beading down her face as she tried to keep herself calm to no avail. Awful flashbacks of her time in chains years ago flashed before her eyes. How she watched her siblings die or go insane one by one in front of her. How she couldn't do anything thanks to those damned chains. How her father—

"El."

She snapped out of her panicking for a brief second upon hearing the pet name. She turned her head to the source of the voice.

On the other side was Byleth, also chained to the wall. His wounds from being held captive before she arrived remained, and Edelgard could now see how deep the gash on his chest was. She flinched as she saw small drops of red around his sitting form.

"Byleth," Edelgard gasped.

"El, calm down," Byleth whispered, his voice low in an attempt to soothe her. "Take a few deep breaths, dear."

Edelgard did as she was told. The first breath was shaky, but she managed to breathe out through her nose. After a few more deep breaths, her heart began to slow and the panic waned. She sighed in relief.

"Are you okay?" Byleth asked.

Edelgard nodded, but gritted her teeth when she felt pain flaring up from her chest. The spell definitely left a wound there. "I… I'll be okay. How about you?"

"I'm fine. Just… scared for you." Byleth admitted.

"Scared?"

"Do you remember? Thales took me hostage to draw you out, and he caught you and brought us to Shambhala. When he shot that spell at you, I thought…" He sighed, shaking his head. "Forgive me, El. I shouldn't have dragged you into this…"

"Love," Edelgard began, her eyes filled with worry. "It is not your fault. It was mine for not thinking. If I had been more careful, you would have been safe. We would have been safe."

"El…" Byleth trailed off. With one leg, he reached towards Edelgard in an attempt to comfort her. With both of them being chained, that was all he could do. Edelgard, knowing what he was doing, stretched her own to touch his foot. Touching him helped Edelgard calm down completely, and Byleth could feel that as he smiled a small, comforting smile. "I'll find a way to get us out of this. I caused this, so it would be fair for me to get us out. I promise you that."

"Don't make promises that you would never keep, professor."

The two turned their heads upon hearing the familiar, deep voice of Thales. The older man opened the door to their cell, carting in a small table. While neither of the two captives could see what was on the table, they both knew that there was something there to make their day worse.

"Thales," Byleth growled. "What do you plan on doing to us?"

"Isn't it obvious?" Thales chuckled. "Both of you bear Crests. It is only fitting I do some experiments on you both."

Edelgard's panic attack began to flare up again, but she held back as best as she could. She couldn't show Thales that she was frightened, that she wouldn't want to go through this again. She had dealt with enough Crest experiments in her life.

Byleth tapped her foot with his own, in order to let her know that she was all right. He turned to her, his eyes practically telling her to stay strong.

"Aaaaw," Thales cooed mockingly, "isn't that sweet? You two are quite fond of each other."

"If you're going to do any experiments on us, experiment on me, Thales." Byleth demanded.

"Byleth!" Edelgard gasped, not wanting to believe what she was hearing. She didn't want to see him go through what she had gone through in her past. No. She couldn't. "It's me you want, isn't it, Thales? Experiment on me instead!"

"Edelgard, don't!" Byleth cried.

"Hmm…" Thales hummed, a finger on his chin. He thoroughly glanced at Byleth's condition, then at Edelgard's. With a menacing grin, he began, "You both have good arguments. However…"

He turned to Byleth, who glared at their captor. "I heard that the Crest of Flames has… interesting effects." From the table he carted in, he took a small knife. Edelgard froze, her eyes never leaving the knife. Byleth also watched carefully as Thales approached him with the dangerous weapon. "Let's test it out, shall we?"

"NO!" Edelgard screamed, now thrashing against her chains.

Alas, it was no use, as slowly, Thales slit Byleth's arm deeply with his weapon. Byleth bit his lip so hard he drew blood from the pain, and only a grunt left him. Blood dripped down from the deep wound he had sustained, but Byleth didn't make another sound from that.

"Painful, isn't it?" Thales taunted.

"Damn you." Byleth cursed under his breath.

Without warning, a sharp pain hit his leg, and Byleth cried out from the sudden attack. Thales stabbed his leg once, then again, then a third time, nearly severing an artery in each stab.

"I dare you to say that again," Thales threatened in Byleth's ear.

"Enough, Thales!" Edelgard cried. "You're going to kill him!"

"Oh, I don't intend on doing so, Emperor," Thales reminded her. "What use is a test subject if I killed it?"

"Damn. You." Byleth repeated with a weak glare.

Another sharp pain, this time, on his stomach. Thales' knife dug deep into his stomach, and Byleth screamed out bloody murder. When Thales pulled out the weapon, Byleth began to breathe heavily, and Edelgard could see blood dripping down from his mouth.

"Byleth," Edelgard pleaded. "Stay with me!"

"Shush, Emperor," Thales threatened, his knife now pointing at her neck. Edelgard froze, her eyes never leaving the weapon that threatened her life. "Unless you want to suffer?"

"Stay away from her!" Byleth barked, but stopped when he coughed up blood. He spat out the excess, and gagged as some of it went down his throat. The coppery taste remained in his mouth as he nearly retched.

"Shut up!" Thales yelled, another spell forming on his fingertips. Without warning, another Death Γ spell hit Byleth squarely in the stomach, opening his wound more. Byleth screamed—his loudest one yet—as he whimpered in pain. Despite that, however, he glared up at his captor, as if daring him to do it again.

"Tough man," Thales chuckled. "Jeralt taught you well."

The mention of his deceased father's name made him growl in anger. How dare he say his father's name in a mocking manner. "Leave. My father. Out of this." He growled.

"I can do whatever I want," Thales said with a smirk. "You're my test subject."

He approached the chained up professor, and that was when Edelgard snapped. As she began to threaten and beg Thales to leave her husband alone, to hurt her instead, Thales took out a key from his pocket. Byleth raised a brow when Thales unlocked the chains that held Byleth's arms above him. The moment the chains were loosened, Byleth lunged. He was weak, yes, but he had to try and attack Thales.

Thales, however, stopped him by grabbing his injured arm and twisting it. Byleth cried out in pain before Thales threw him to the hard, cold floor. Edelgard gasped, her eyes wide at seeing this.

"Don't do anything stupid, professor," Thales warned. "Unless you want me to torture her instead?" He turned to Edelgard, who was writhing against her chains in order to reach Byleth.

"I… won't let you," Byleth growled, sitting up. The pain flared up around his body, and he cringed—he didn't bother hiding it from Thales due to how bad it was.

Thales turned to the table, before he took what appeared to be a whip from there. Byleth's eyes widened at the new weapon.

When Thales raised the whip, Byleth shut his eyes, expecting to be whipped for his troubles, only to hear a sound in front of him. He opened his eyes, only to see the weapon within his reach.

"I heard that the Crest of Flames can heal the bearer when they strike an opponent," Thales began, pointing at the new weapon. "See that whip? Use it. But not on me."

He pointed at Edelgard, who froze when she knew what he was talking about. "Use it on her."

"What?!" Byleth gasped. He couldn't believe his ears. Hurt Edelgard? No. He couldn't. He wouldn't. He would never harm his wife that way.

"Do it now," Thales growled impatiently. "Do it or else!"

"Never!" Byleth yelled. "I'd rather you take my life than have me hurt my wife—"

He was met with a strong kick to his stomach, and Byleth gasped and coughed up more blood. After a moment of coughing, he then retched on the floor. He gagged, gasping for air once he was done.

Edelgard turned away from seeing the vomit mixed with Byleth's blood, and her stomach turned. The putrid smell hit her nostrils, and she nearly vomited herself. She gagged, but held on as she tried not to smell the odor that was in the air.

"Do as I say, test subject," Thales demanded, stepping over the bloody vomit to reach Byleth. He took the ex-mercenary by the chin and forced him to look at Thales in his eyes. "Or else."

Byleth breathed heavily, trying to gulp in as much air as possible from his retching fit. He gave Thales a weak glare, and he growled. He wasn't going to back down and harm his wife. He refused to do anything that heinous towards the woman he loved.

"Byleth."

Byleth turned to Edelgard's chained form. Her eyes were filled with tears, but Byleth could tell she was struggling to stay strong.

"Do… do as he says. He'll hurt you if you don't do it."

Byleth shook his head. "No, El! I can't hurt you! I won't hurt you!"

"Byleth, listen to me," Edelgard said, her tone firm. "Do what he tells you to do. I'll be alright. I won't stop loving you when you do it. Please, Byleth. For me?"

Byleth could only stare at her in disbelief. He couldn't hurt her. What kind of person would he be if he harmed someone he loved?

But if it was for Edelgard herself?

He had to. He didn't have a choice.

"Do it, boy," Thales threatened, grabbing Byleth by the hair and pulling him to his shaky feet. "Or suffer."

Byleth nearly fell from his injuries, but he kept his footing as he slowly approached the chained-up Edelgard. He unfurled the whip by swiftly whipping it to his side, and a loud crack echoed in their cell. Byleth could have sworn he saw Edelgard flinch at the sound, but he chose to ignore it. This was for Edelgard, even if it meant harming her.

"El," Byleth whispered, "please forgive me."

"I already have," Edelgard answered with a small, comforting smile. "Do as you must."

Byleth gulped, before raising his whip. He closed his eyes, not wanting to see the pain he was about to inflict on his wife.

CRACK

Edelgard's piercing screams echoed in their cell, and Byleth froze. He opened his eyes, and he gasped upon seeing what he had done.

The wound Edelgard sustained from Thales' spell hours ago opened up thanks to the whip, a large amount of blood dripping down from her chest. Edelgard cried and whimpered, tears now falling from the pain.

"EL!" Byleth cried. "Oh Sothis, I am so sorry!"

"Again." Thales said.

Byleth turned to Thales, his teeth gritting. He raised his whip, ready to strike down Thales for forcing him to do such a heinous act. "DAMN YOU!"

He struck with the whip, only for Thales to simply grab the tip like it was nothing. He frowned, unsatisfied by his test subject's disobedience.

"Disappointing," was all Thales said before another Death Γ spell bubbled on his fingers. Before Byleth could react, the spell hit him on his stomach. He crumpled to the ground, convulsing in pain. Blood splattered on the walls as Byleth held in another retching fit.

"BYLETH!" Edelgard screamed.

"Attack her, not me, boy," Thales reminded in a harsh tone.

Byleth struggled to stand, before turning to Edelgard, his whip ready. Edelgard didn't try to move away or even cower in fear; she knew that doing so would discourage Byleth.

"Again, test subject," Thales ordered.

"N-no," Byleth shook his head, his lip quivering. "I-I can't—"

"Byleth," Edelgard spoke. "Do it."

"El—"

"JUST DO IT!"

CRACK

Byleth didn't want to be reminded again. He whipped Edelgard again, this time on her shoulder. He kept his eyes opened so he wouldn't make the same mistake of opening her chest wound again. Edelgard bit back a cry of pain, her eyes begging Byleth to keep doing it till Thales was satisfied.

CRACK, CRACK, CRACK

A few more whips. To Edelgard's credit, she only made small whimpering sounds as Byleth reluctantly whipped her over and over. This still broke Byleth's heart, however. The fact that he was harming Edelgard hurt him more than it hurt her.

When he readied the seventh whip, a green glow illuminated around his body. The moment he whipped Edelgard's left arm, the glow closed up the knife wound on his arm he had sustained just a few minutes ago. It was like he wasn't sliced from there in the first place.

My Crest.

"Enough."

Byleth practically threw the whip on the ground upon hearing Thales' command. He watched Edelgard curled up on herself, whimpering in pain. Byleth got to his knees in despair, tears threatening to fall as he studied what he had done to his wife.

Whip marks littered her body, and blood slowly dripped down from her fresh wounds. Edelgard gasped when her left arm touched the cold stone wall, and she sobbed in pain.

El… forgive me.

Thales forced Byleth to stand and face him, before he grabbed his arm. He examined it, noticing that the wound he gave Byleth had disappeared. No trace of blood was found on his skin.

"Interesting…" Thales hummed. "As I suspected. If the Crest bearer was injured, they could heal themselves by attacking an opponent."

"You're disgusting." Byleth spat.

Thales simply ignored Byleth's venomous insult before he released his hold on his arm. He pointed at Byleth's corner where his chains hung, like an owner scolding their dog. Byleth, looking back at Edelgard's slumped form for a moment, walked towards the area Thales pointed at. He lowered his head, guilt building up inside him over what he had done. Thales followed behind him, and when Byleth sat back down on the cold, hard floor, Thales forced his arms back up before placing the chains on his wrists again.

Edelgard could only watch as her Byleth was chained up again. She whimpered, the pain unbearable for her to deal with. She shivered—whether from the cold or from fear, she wasn't sure.

Byleth's gaze turned to her, a silent apology dancing on his lips. He shouldn't have harmed her, even though she begged him to do so. He would rather be hurt or even die than to see her in this much pain.

It broke his heart, seeing his El like that.

"I'll be back tomorrow," Thales said, taking the table before turning to the door. "Get as much rest for tomorrow's next experiment, test subjects." With that, he left the room, slamming the door behind him. A small click reached both of the captives' ears, and it echoed somewhat around them.

Silence reigned around the area for a few minutes. Then.

"El?"

Edelgard glanced up at Byleth, tears still streaming down her face. Seeing such a sight shattered Byleth's already broken heart. This is all my fault.

"Forgive me for what I have done, my love," Byleth whispered. "I hope… I didn't hurt you too bad."

Edelgard merely smiled, despite the pain flaring up everywhere in her body. "I already forgave you before you did it, my love. It's okay. I'll be alright."

This time, she reached out with her own foot despite the pain, and Byleth happily reached out the same way. They touched feet, and Byleth's guilt began to flush away. Things were going to be okay. Soon, help would come. Byleth was sure that Hubert had already gathered up an army to come and rescue them. All he and Edelgard had to do was wait and hang on. For her.

"I love you, El."

"I love you too, Byleth."

I won't let you get hurt ever again, El. That's a promise.

Constructive criticism is welcomed!