The Fallen Heir's Vow
The image he projected was that of a noble young master. Back straight, chin slightly raised, eyes cast down with haughty disdain. In that pose, he met Rydia's gaze directly and spoke.
“Sir Rydia.”
“……!”
Rydia’s half-lidded eyes flew wide open. For the usually expressionless knight, it was the closest thing to an extreme display of emotion. Seeing the tremor in her crimson irises, he realized it would take her a moment to regain her composure. He used that opening to quickly solidify the setting. This was his specialty, after all.
Let’s see… He was dressed as an adventurer, so a common noble wouldn’t do. A fallen noble, then. One driven from power by political intrigue. A family that still held its title, but nothing else. His parents had been assassinated, and his sole remaining younger brother had become the enemy’s concubine in exchange for sparing his life. The day after their first night together, that brother took his own life. What exactly happened was unclear, but one thing was certain: only he remained. Only he could restore the family name. Only he had the right to exact revenge. For that purpose, he would do anything. He would grasp a sword he had never held before, mingle with adventurers he had once looked down upon, and even exploit a young knight who still knew little of the world. He would never refuse.
…Right. It had turned out a little darker than intended, but a fallen noble heir needed at least this much backstory. The concept of a sheltered noble playing at adventuring with only a single knight escort wasn’t bad either, but what mattered here was how well it satisfied Rydia’s romantic fantasies. And a knight would surely prefer serving a lord with a tragic past and standing at the forefront of his revenge rather than babysitting some naive young master. There was the minor issue that he didn’t actually know proper noble etiquette, but this was just a performance. As long as it felt plausible, it would be enough.
Once the image in his mind was solid, he acted it out exactly.
“I want you, Sir Rydia.”
***
Rydia drew a sharp breath. The Yona she knew was a small, adorable pink-haired boy whose actions were anything but. Despite his dark past, he tried his best not to show it, and though he had learned communication in a slightly twisted way, he was still quick to trust others. His background gave him a lively charm, but he was hardly what anyone would call a young master. So what about the Yona standing before her now?
His posture was rigid, as if he would rather break than bend. Though he was technically looking up at her, it somehow felt like he was looking down. A fierce will burned in his pink eyes—solid and heavy like stone, unshaken by any storm. The completely transformed Yona opened his mouth.
“I want you, Sir Rydia.”
“…Huh?”
While the flustered Rydia let out a foolish sound, Yona closed the distance with light, measured steps. Not fast—rather slow, in fact. Precisely because of that, every step drew the eye. A bitter smile formed on his lips as he came to stand right in front of her.
“Of course, there isn’t much I can offer you. I have no fine weapons, no lofty honors, not even a single patch of land to grant.”
The words could have sounded pessimistic, yet there was no negativity in Yona’s voice. They rang out plainly, as if he were simply stating facts.
“Instead, I will give you everything I have.”
“What…?”
Rydia reflexively furrowed her brows. She had told him not to make any lewd advances, and she thought he had just broken that rule. It was a hasty judgment, however.
“Oh my. Are you interested in my body? That’s not a bad idea either. If you need it, I’ll give it to you anytime. …Just not right now.”
In that instant, Yona’s atmosphere shifted again. Until a moment ago he had radiated the calm, elegant weight of a true noble heir. What emanated from him now was something far more viscous.
“Sir Rydia. You told me you wouldn’t abandon me. That you would always stay by my side. Did you mean it?”
“…Yeah.”
Her head was still a mess, but Rydia answered reflexively. Regardless of everything else, her desire to help Yona was genuine. It wasn’t because of Elly’s request or because it was what any aspiring knight should do. At some point, Rydia had come to feel pity for him. She knew his past. She understood how far removed he was from common sense, yet she had seen him struggle to find happiness like everyone else. Wanting to help someone like that was only natural for any decent person. There were exceptions, of course, but at least for Rydia, it was true.
Perhaps he had seen straight through her shallow feelings. Yona’s eyes curved like crescent moons.
“Then would you be willing to fall with me all the way to the bottom of hell?”
“…What?”
His smiling eyes looked both amused and sorrowful. The meaning within them was clear: anyone who stepped forward with half-hearted resolve would come to regret it deeply. It was neither his usual playfulness nor the conviction he had shown moments earlier, but something raw and unfamiliar. Overwhelmed by the sheer density of that emotion, Rydia heard his voice at her ear.
“If you would do that for me, then I will give you everything.”
“Everything…?”
“Yes. Do you want my body and soul? Or perhaps fame that stretches from the highest peak to the lowest depths? I’ll hand you any divine weapon sleeping in the labyrinth. …That is, if you become the vanguard of my revenge.”
“……!”
Only after hearing those final words did she understand the emotion in his eyes. A violent thirst for vengeance that seemed ready to burn the world and himself along with it.
‘…I was wrong.’
She had thought that since he had already escaped Those Who Swallow the Twilight and been freed from brainwashing, all she needed to do was teach him how to live normally. But that wasn’t the case. After everything he had been through, there was no way he could simply laugh and move on as if nothing had happened. Revenge. Only revenge could truly free Yona from his past.
Rydia stared blankly at him. What stood before her was neither a pitiful child nor a slightly lewd and cute boy. It was a starving avenger. An incomparably beautiful ghost slowly extended its hand. The gesture was simple—offering the back of its hand toward her—yet every detail followed noble etiquette to perfection. Even Rydia, born to a humble knight family, could find no fault in it. Already dazed, she was struck by yet another shock.
Those Who Swallow the Twilight were a heretical cult of fanatics, but their roots lay in the priesthood. They might teach priestly rites, but they would never teach noble etiquette. So what exactly was this graceful, fluid movement she was witnessing?
‘I… don’t actually know everything about Yona.’
She knew he had been kidnapped by the cult as a child. But what about before that? Was he truly just a back-alley orphan? If he was an orphan, then who were his parents?
In truth, because this world had taken shape according to Yona’s own detailed setting, the etiquette had naturally followed what he imagined. It was merely that his casual thought of “this is probably how nobles act” had aligned perfectly, but Rydia had no way of knowing that.
Already reeling from countless shocks that day, Rydia found herself speechless once more. Yona extended his hand toward her as if urging a choice.
“……”
“……”
No words passed between them. In the silence, only unshakable trust remained. Yona truly believed that with Rydia by his side, he could achieve his revenge. The moment she realized this, a spark ignited in her chest.
A knight offers her life for the one who recognizes her worth. And now, standing before her, was someone who trusted her more than anyone else in the world—perhaps even more than himself. It was an impulsive act, yet she surrendered to the certainty that she would never regret it.
Click.
Rydia dropped to one knee and accepted Yona’s hand. As if he had been waiting for this, a clear voice recited the ancient words of the oath.
“I declare: my will shall be your will, and my glory shall be your glory. Therefore, become my proxy.”
“I swear it here. I offer everything I am to fulfill your will. Please accept my sword.”
After gently kissing the back of his hand, Rydia drew a longsword and presented it to him. Yona took it with both hands, kissed the blade once, then lightly rested it on her shoulder. His voice, laced with gratitude and apology yet masked by playfulness, whispered,
“With this, we’re accomplices, Sir Rydia.”
“Ah…”
Rydia realized in a daze what she had just done. Yona helped her to her feet and returned the sword.
“I have a request for my loyal knight, Sir Rydia.”
“What… is it?”
While Rydia awkwardly added honorifics, Yona—already back to his usual self—grinned wickedly.
“Please cut the hide with aura!”
“……?”
The sudden rush of reality hit her like waking from a dream. Still dazed, Rydia tilted her head as Yona puffed up with pride.
“I won, right? So hurry up and get that Iron Wolf hide with aura! We’re not wasting eighty coppers like this!”
“……”
Rydia silently closed her eyes.
‘My first time (oath)…’
It felt like she had just suffered through a terrible nightmare.