Know Your Enemy.

Draco Malfoy was the "Prince of Slytherin".
He thought he owned the place, and believed that everyone should bend to his every whim.
That was until he met Skye Weasley.
She's the daughter of a Muggle lover, neice of a Muggle lover.
On top of all that, she was a Weasley.
Skye meets Draco and teaches him the life lessons he happened to ignore.
Like common courtesy, manners, morals.
You know, the little things.
She also taught him that sometimes life can be a bitch.