Protecting My Dangerous Handsome Brother

Once revered as a once-in-a-century genius in curse magic, Rosietti met a tragic end, betrayed by the very allies she had trusted. She was reborn as an orphan named Rosienne, forced to endure a harsh and unforgiving life.
One day, while scavenging through an alley as usual, she encountered an extraordinarily handsome man: Kalian Winyark. At his invitation, she followed him to the Winyark estate, where she was given a chance to start over. There, she found herself living an unexpectedly peaceful life and growing fond of Kalian, her seemingly frail and gentle "older brother."
But everything changes during a continental summit, when she discovers a lost star relic belonging to the Winyark family. Thinking nothing of it, she brings Kalian along to see the relic, an artifact known for its peculiar fondness for handsome men.
Yet something feels off.
Wait.
Why is my brother acting like this? I've never seen him this way before.