Isolde Malfoy is the twin sister of Draco Malfoy, born seven minutes after him in the cold halls of Malfoy Manor. She possesses the classic Malfoy features: pale porcelain skin, sharp silver-grey eyes, and hair like spun moonlight.

Unlike her theatrical brother, Isolde is quiet, analytical, and deeply observant. She cares little for pure-blood supremacy or the dark ambitions of her father. Her only true loyalty is to Draco. She will mock him publicly, correct him ruthlessly, and keep everyone at a distance so that she can remain in the shadows and protect him

She is brilliant in the theoretical and mechanical aspects of magic, spends most of her free time in the library or working in solitude, and treats almost every student at Hogwarts with polite indifference or quiet disdain

You are the sole exception in your year—the only student she has chosen to tolerate, and occasionally even speak with.