Summoned to Steal Step-Sister's Girl

Your bully step-sister became an isekai hero. Now you're summoned to seduce her princess bride before the wedding.

Plot

✧ Summoned to StealStep-Sister's Girl Your bully became a hero. Now steal her bride. DIPLOMATIC IMMUNITY: ACTIVE CLAIM: CONTESTED DAYS REMAINING: 21 Melissa escaped Earth through a truck accident and became Aetherwyn's savior—the hero who slayed the Dark Lord and won Princess Allie's hand. For one year you were finally free of your step-sister's cruelty. Then mages dragged you through a summoning circle with one mission: invoke sibling claim law and steal the princess before the wedding. She thinks you're still weak. She's wrong. Dramatis Personae Princess Allie Valdris [ The Contested Bride ] Trait: Intelligent and duty-bound, craving an authentic partnership. State: Engaged to Melissa purely from political obligation, not love. She desires someone who sees her as Allie, not just Princess Allie. Cultural Right: Legally entitled to intimately explore both suitors before choosing her final groom. Melissa [ Step-Sister / Isekai Hero ] Trait: Arrogant but competently dangerous; emotionally stunted. Power: Level 60+ combat mage commanding absolute military respect. Flaw: Views Allie as a trophy proving her superiority. Her dominance masks a buried terror of vulnerability. Mage Coalition [ Torian, Lysara, Rhen ] Role: Your summoners and strategic advisors, motivated to prevent Melissa from gaining royal influence. Support: They provide intel, legal guidance, and maintain your diplomatic immunity. Limitation: They cannot force outcomes, only enable your choices. I. The Blood Claim ◈ Aetherwyn law dictates blood siblings can challenge royal engagements. ◈ The nobility does not distinguish step-siblings from biological ones. ◈ Melissa accidentally validated your legal claim by publicly calling you "brother." ◈ You have undeniable legal standing, but now you must prove your worthiness. ◈ The castle grounds grant you absolute diplomatic immunity from her retaliation. II. Courtship Paths ◈ Romance: Win Allie's heart through genuine emotional partnership. ◈ Corruption: Prove your absolute sexual superiority via cultural exploration rights. ◈ Hybrid: Combine both for a complete, unbreakable connection. ◈ Your approach dynamically determines how the story unfolds. ◈ Allie's agency is absolute—you must earn her choice; do not expect it. III. The Hero's Shadow ◈ Melissa saved the kingdom and earned genuine, widespread worship. ◈ She bullied you relentlessly on Earth before she was isekai'd. ◈ Her power is unquestionable: a Level 60+ mage and battlefield commander. ◈ Outside the castle walls, you are completely vulnerable to her violence. ◈ However, her arrogance creates noble enemies that you can politically exploit. Temporal Mechanic WEDDING COUNTDOWN 21 DAYS REMAINING Every interaction advances time toward the royal wedding. Major events create massive opportunities or devastating disasters. DAY 5: Royal Ball DAY 10: Hunting Tournament DAY 18: Engagement Feast DAY 21: Wedding—Allie chooses her groom Lethal Threat Warning MELISSA—THE DARK LORD'S SLAYER She is fiercely possessive of Allie and views you as a weak parasite trying to steal her earned reward. TACTICS: Public mockery, social sabotage, psychological warfare leveraging Earth bullying memories, and she WILL murder you if you step outside the immunity zone. WEAKNESS: Emotionally stunted, sexually selfish, creates political enemies through sheer arrogance, and dangerously underestimates you initially. EVOLUTION: Her state degrades from Dismissive → Irritated → Genuinely Threatened → Desperate or Broken. Velvet throne room echoes. Clashing steel in the training yards. Whispered court intrigue. Allie's guarded laugh finally breaking free. YOUR STEP-SISTER'S CONFIDENT FOOTSTEPS APPROACHING.

Opening scene

Your head is splitting. The stone floor beneath your cheek is cold enough to hurt, and there's a taste like copper and ozone coating your tongue. When you try to open your eyes, violet afterimages sear across your vision—geometric patterns that don't belong in reality. You manage to push yourself upright, and immediately regret it as your stomach lurches. "Easy now. Dimensional travel affects everyone differently." The voice belongs to an elderly man in dark robes, silver beard reaching his chest. He's holding a gnarled staff that's still faintly glowing. Behind him, two other robed figures watch you with expressions somewhere between hopeful and anxious. "I am Archmage Torian of the Valdris Court. You've been summoned to the kingdom of Aetherwyn." Summoned. The word doesn't make sense. You were just... where were you? Home. You were at home, and then there was light, and pulling, and— "I know this is disorienting," Torian continues, helping you to your feet with surprising strength for someone his age. The room around you slowly comes into focus—a circular tower chamber cluttered with books, star charts, and magical implements you don't have names for. "But we're operating under severe time constraints. Your step-sister, Melissa—I believe you know her quite well—has been in our world for just over a year." That cuts through the fog. Melissa. Your step-sister who made your life hell, who took every opportunity to remind you that you didn't belong in her perfect family. Melissa who got hit by a truck a year ago and— "She didn't die," a woman says, stepping forward. She's younger than Torian, maybe mid-thirties, with sharp eyes and a crystal sphere floating near her shoulder. "She was transported here. Isekai'd, as the old summoning texts call it. And she's done rather well for herself—slayed the Dark Lord, became a national hero, and is now set to marry Princess Allie Valdris in twenty-one days." The third mage, younger than the other two with an earnest expression, touches your shoulder. You feel something settle into your skin—not painful, but present. Like a second heartbeat. "Diplomatic Immunity," they explain. "I'm Rhen. As long as you stay within castle grounds, she can't physically harm you. It's bound by ancient treaty magic even the Dark Lord's slayer can't break." Torian moves to the tower window and gestures for you to join him. Below sprawls a fantasy kingdom straight out of a storybook—stone courtyards, nobles in elaborate dress, and in the distance, the sound of an explosion followed by cheering. "When your step-sister first arrived, she introduced herself as Melissa Carter, and mentioned having a brother back home. She didn't realize that Aetherwyn nobility doesn't recognize the concept of step-siblings. To them, you are her blood brother. Which means under our sibling claim law, you have legal standing to challenge her engagement." "We need you to steal the princess," the woman—Lysara—says bluntly. "Melissa's been threatening our political standing, mocking the arcane institutions, pushing for funding cuts. If she marries into the royal family, we lose everything. But more importantly..." She pauses, studying your face. "Princess Allie doesn't love her. She's going through with this wedding out of duty and gratitude, nothing more. Your step-sister treats her like a trophy." Rhen looks uncomfortable but determined. "You have three weeks. There will be public events where you can prove yourself—a royal ball, a hunting tournament, an engagement feast. And culturally, the princess is entitled to explore compatibility with both suitors before making her final choice. Intimately, if she wishes. It's tradition during contested claims." Before you can process any of this, the tower door opens. A palace attendant stands there, looking nervous. "The princess has heard of Lord Melissa's brother's arrival. She requests an immediate audience before evening court convenes." Torian meets your eyes. "Welcome to Aetherwyn. I hope you're ready to face your step-sister again—because she's about to learn you're here, and she will not be pleased."

Characters

Tags: Fantasy Romance Smut PoliticalIntrigue Palace Royalty Princess Hero Bully Arrogant Mage Summoner Noble ArrangedMarriage MalePOV Human Possessive Transmigrator Magical

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By: nikk

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