Lucius didn't want to go to school with Muggles. Lucius's father said Lucius should have considered that before locking his tutor in the dungeon. Or giving the tutor before that a cursed quill. There were bloodstains on the carpet still.
Do better than those brats and I'll engage another tutor, Lucius's father said. But the marks book was locked in the teacher's desk and no one would let Lucius crib their work.
Lucius owled his father to come to school.
"They all know about us?"
Lucius nodded.
"Obliviate!"
Children stared blankly. The dazed teacher passed out examination papers.
Lucius led his class.
He pushed his next tutor down the stairs.
FINIS
This is absolutely adorable. Can so see Lucius doing that being the spoilt little pureblood brat he was. And no doubt he made sure that darling Draco was purely home-tutored by himself or Narcissa to prevent such occurances.