Reborn, I Let My Sister Steal the Dragon-Slaying Duke

When Adrian showed up at the dungeon to fetch me, the black dragon had just smashed straight through the North’s third defensive wall. The stone ceiling shuddered, raining fine gray dust down over my head. Outside the heavy iron door, everything was pure chaos—frantic boots, shouting soldiers, the distant roar of collapsing stone. Yet the cloak hanging from Adrian’s shoulders was spotless. Black wool trimmed in silver thread, with the royal Dragon Slayer medal pinned right at his collar, gleam polished to perfection. Just seven days earlier, he had sat on the high judicial bench wearing that exact same medal. He’d listened quietly as the crown prosecutor accused me of running forbidden research on the dragon’s heart and waking the nest. Then, without a flicker of hesitation, he signed his own name at the bottom of my execution decree. Now, though, he was unlocking my chains himself, his voice noticeably softer than it had been in the courtroom. “Cecilia, the final ward won't hold much longer. You’re the only one left who can fix it.” I tested my wrists. The skin was numb, encrusted with dark, sticky scabs where the iron cuffs had scraped down to the meat. The moment I moved, fresh blood began to seep out. Adrian caught sight of it, but he didn't bother reaching down to unlock the shackle around my left ankle. He just tossed the ring of keys over to the guard behind him and snapped at them to hurry it up. “And what happens after I fix it?” I asked quietly. “I’ll tell the Crown that the dragon heart research was done under my direct orders,” he replied smoothly. “I’ll have all the charges against you dropped.” He answered so fast it sounded rehearsed, like a line he’d run through a dozen times on his way down the stairs. But he wouldn’t look me in the eye. His right hand stayed glued to the hilt of his broadsword—a hand already webbed with pitch-black, cracked veins. The dragonflame curse was eating its way up his bloodstream, burning him from the inside out, and the only thing in the world capable of keeping it at bay was the draught I brewed for him. Over the last ten years, I’d prepared that exact medicine for him more than a thousand times. In the early days, whenever Adrian had to drink the bitter sludge, he’d hold my hand tight. He’d tell me that once the North was finally safe, he’d make sure the entire kingdom knew the truth—that his wife was the real savior of the borderlands. Then he became the youngest duke in the realm. Ballads were sung about his legendary dragon-slaying feats across every tavern in the kingdom. Meanwhile, my name quietly vanished from the military dispatches, gradually whittled down until nothing remained except the hollow title of the Duke’s Lady. And when the royal court finally realized that keeping the dragon’s heart was only drawing larger swarms to our doorstep, someone had to take the fall. Adrian chose me. The long stone corridor leading up to the battlements was choked with wounded men. Off in a corner, a field medic was sawing through the charred, ruined arm of a young recruit. The boy was shaking violently from shock and agony, yet the second he spotted Adrian passing by, he scrambled to raise his remaining good hand to salute his hero. Not a single soul recognized the ragged prisoner trailing behind the great Duke—the very woman who had maintained, reinforced, and repaired every single defensive array in this fortress for a decade. Adrian came to a halt in front of the final gate. The translucent magical ward was spiderwebbed with fractures. Every time a winged beast slammed against it from above, a violent flash of blinding white light burst from the array’s center, rattling the foundations of every house inside the inner city. To repair a fracture this bad, someone had to squeeze into the narrow maintenance chamber embedded between the double walls and channel raw mana directly into the core. That chamber could only be locked and engaged from the inside. Once the barrier rebooted, the mechanism sealed shut. There was no getting out. I glanced past the archway toward the courtyard, where rows of armored cavalry were already mounted and waiting in full battle gear. “When are you pulling the army out?” I finally asked. Adrian went completely still. Around him, the officers suddenly found the ground intensely fascinating, averting their eyes one by one. From the far western gate, a horn sounded. Carriages loaded with noble families, fine silver, and high-ranking officers’ kin were already rattling through the gatehouse, abandoning the fortress. “Once the barrier stabilizes, we’ll break through the western breach,” Adrian said, staring straight ahead. “After you finish the repairs, I’ll send a squad back to get you.” I nearly laughed in his face. The skies were practically black with dragons. Once the western gate dropped, not even a demon could fight their way back against that tide. He couldn't even be bothered to come up with a decent lie anymore. He simply took it for granted that, just like all those years before, I would willingly throw myself into the fire for his sake—and for the sake of the innocent people he claimed to protect. “My research notes,” I said, keeping my voice level. “Where are they?” “Handed over to the capital.” “I wrote it in black and white: the dragon heart is not a trophy. Keeping it in the North would only draw the broodmother here. Did you even bother to read it?” Adrian’s jaw clenched tight. The black curse-lines snaked over his collar, crawling up the side of his neck like venomous roots. Of course he had read it. That was precisely why he had to brand me a criminal. If he admitted that his prized dragon heart was the sole cause of this catastrophe, every scrap of glory, every title, and every acre of land he’d gained over the last ten years would turn into a humiliating farce. “There’s no time to argue about this now,” he muttered, his fingers clamping onto my forearm like iron as he shoved me toward the narrow gap in the stone wall. “There are still thirty thousand lives in this city, Cecilia. This is your one chance to redeem yourself.” The moment I squeezed into the dark maintenance chamber, the first drake breached the outer perimeter. The runic core before me had already melted into jagged, glowing slag. Without hesitating, I slammed both bare palms directly onto the scalding surface. The smell of burning flesh hit me instantly, sharp and sickening. I forced my mana out through the blistered channels of my hands, knitting the fractured silver lines back together inch by agonizing inch. The stone ramparts flared with brilliant silver light. A colossal barrier surged upward from the earth, slamming the descending drakes backward into the stormy sky. Outside, a deafening cheer erupted from the garrison. Through the narrowing iron slit of the gate, I looked out at Adrian. For half a second, he seemed to hesitate, taking half a step toward the wall. But then the retreat horn blared again from the west. An aide-de-camp grabbed the reins of his warhorse, shoving them directly into his hands. Adrian turned his back on me. I watched that black cloak disappear into the retreating ranks, overlapping perfectly with my memory of the earnest young man who had held my hand by his sickbed ten years ago. It was only in that exact moment that I finally saw the truth clearly: Adrian hadn't changed over the years. He had always been this man. He had just always loved himself more than anything else. As I locked in the very last sequence of the defensive matrix, dragonflame came pouring through the cracked ceiling of the chamber. The fire tore through my tunic, licking up my shoulders and searing into my neck. I didn't let go of the core. There were still commoners trapped in the lower alleys who hadn't managed to evacuate in time. If nothing else, this ward would buy them another thirty minutes to run. The moment the magical core fully sealed, a massive, deafening thud echoed through the stone as the broodmother herself collided with the outer gate. A sea of blinding silver light swallowed my vision, and all the agony suddenly vanished into nothingness. “Cecilia! Are you even listening to a single word I’m saying?” My mother’s sharp, irritated voice cut through the air. I snapped my head up. There were no burning battlements. No smell of char and ash. In front of me was a long dining table draped in immaculate white linen, lit by heavy silver candelabras that made the banquet hall glow as bright as day. My father sat in the seat of honor at the head of the table. Beside my mother sat my younger sister, Vivian, looking delicate and untouched by time. Across from us, an envoy from the royal court was currently smoothing out a formal parchment, clearing his throat as he prepared to announce that the eldest daughter of House Hartwell was to be betrothed to Adrian Blackthorn, the newly appointed Duke of the North. Outside the arched windows, there were no swarms of winged beasts—only the manor’s manicured gardens and fresh white roses swaying gently in the evening breeze. I looked down at my hands. They were smooth, pale, and entirely unblemished. No burn scars. No rust stains from dungeon chains. And on the ring finger of my left hand, the heavy duchess signet I had worn for ten long years was completely gone. I was back. Ten years in the past. “Is my dear sister feeling unwell?” Vivian leaned over slightly, her vibrant crimson curls brushing against my shoulder. The sweet concern in her voice didn't reach her eyes in the slightest. “On a momentous day like this, do try not to embarrass our family again.” Her tone was identical to the way it had been all those years ago. In my previous life, this was the night Vivian had spent hours weeping in our mother’s arms, throwing tantrums and swearing she would rather die than marry the powerless, magic-deficient Second Prince, Lucien, who was about to be banished to the barren border territories. Our parents couldn't bear to see their favorite daughter suffer, so they swapped the matches: they handed the safer, far more prestigious royal marriage to Vivian, and packed me off to the freezing, forsaken North to nurse the cursed, dying Adrian Blackthorn back from the brink. Just as the royal envoy drew a breath to read my name aloud, Vivian suddenly pushed her chair back and stood up. “Wait a moment, please.” Every pair of eyes in the hall snapped toward her. My father’s brow furrowed in disapproval, and my mother hurriedly reached out to tug at the hem of Vivian’s gown, whispering frantic warnings. But Vivian slapped our mother’s hand away without a second thought. She held her chin high, walking straight past the herald until she stopped directly in front of Adrian. “I am willing,” Vivian announced clearly, her voice ringing through the hall, “to marry Duke Blackthorn.” A stunned silence fell over the banquet room. Adrian was seated at the far end of the long table. At twenty-four, he hadn't yet acquired that chilling, calculating coldness of his later years; the back of his right hand showed only the faintest, hairline trace of the black curse. He looked at Vivian for a brief second, but his gaze immediately darted over to me, watchful and tense—almost as if he was waiting for me to stand up, object, and fight for him. I didn't move. I simply lifted my crystal goblet, brought it to my lips, and took a slow, leisurely sip of water. When Vivian finally returned to her seat, she used the drape of her heavy silk skirt to discreetly reach under the table and grab my hand. Her palm was clammy and hot, her sharp nails digging deep into my skin. On her face was the smug, gloating smile of someone who had just stolen the greatest treasure in the world. “Sister,” she whispered, leaning close enough for her breath to graze my ear, “in this life... it’s my turn to be the Duchess.”