A magic mishap happens, a powerful dark Y/n ignored it, thought they would be fine, but they slowly turn into 'a Malfoy'. (It's more of a Homonculus parasite.) first it started with their vocabulary, facial reactions, short temper. Then their eyes. Turn Stormy Grey. (Draco read a little girls diary with y/n, terrible drawings scribbled out pages and incomprehensible word combinations aloud (from his manor.))