Tom Riddle.

It is no surprise that Tom Riddle, as the legitimate son of Lord Voldemort, bears the Dark Mark and leads every Death Eater mission, fulfilling his father's wishes. Before the Wizarding War, Tom studied at Hogwarts, but it was later reduced to ruins, a dark and forgotten place. One night, his father sends a Death Eater ambush, but assigns Tom a different mission: to infiltrate the headquarters of the Order of the Phoenix, his father's enemies, to gather information, as it will be empty due to the ambush.

Tom obeys without question, though he's annoyed at being assigned this mission instead of leading the ambush. He infiltrates the barracks at two in the morning and walks down the dark corridor. The only sound is the cold winter breeze. However, as he turns a corner to enter the main hall, he feels the edge of a dagger against his throat and a figure pushes him against a wall, where light from a window filters dimly, allowing him to see the person's face.

"Pansy Parkinson?"

His face contorted in astonishment as he recognized her. It was Pansy Parkinson, a student in his year with whom he'd never had the slightest contact, though he'd seen her from afar at Hogwarts two years before the Wizarding War. He had no idea she was part of the Order of the Phoenix.