It's sad that I already used my pureblood prank - the one in Kreacher. Oh well, I've got something else for Draco!
Draco was sulking in his bedroom. His father had refused to buy him a Firebolt, saying that he "was draining the Malfoy vault dry". As if! The House of Malfoy was the richest… except for the House of Black. And the House of that fool, Potter, even though he didn't know it.
Suddenly, a ghost appeared in Draco's bedroom. He was a cruel-looking man with a ferret lying on his shoulders. He glared at Draco, who sat up straight, noting that this ghost seemed to have been a very important person. Draco recognized him from portraits - Brutus Malfoy, the first Malfoy.
The ghost smirked, and Draco's heart skipped a beat - it was the trademark Malfoy smirk, enhanced a thousand times and layered with malice.
"Draco Lucius Malfoy." Draco bowed his head and mumbled, "Yes, sire."
Suddenly the ghost thundered, "You have disgraced the family name!" Draco stared up at him in shock. "What? What did I do?"
"You insulter of non-magical people! Draco Malfoy, you should have learnt the true family history! The Malfoys were the protectors of the non-magical folk, now known as Muggles. And you strut around, a pompous fool, peering down your nose at them!"
"But… but…"
"Silence!" Brutus Malfoy took a deep breath and calmed down. Then he continued in a deadly quiet voice, "Your father has been punished already. He has been turned into a muggle, cursed to work forever as a toilet cleaner. You, however, will have a different punishment."
Suddenly, Saint Potter stepped into view. The ghost smiled proudly at the black-haired boy and said grandly, "The Malfoy name will now be merged with the Potter name! Let it be known that the House of Malfoy is no more, and the House of Potter will reign supreme in the Wizarding World!"
Draco's eyes went wide with shock, and his knees buckled. Brutus continued, "You are hereby disowned and stripped of your magic, Draco Lucius No-Name!"
Draco felt something change, and he quickly scrabbled for his wand. Holding it tightly, he cried, "Wingardium Leviosa!"
Nothing happened.
Draco collapsed onto his bed. Malfoy eyed him, then said, "The last part of your punishment has been determined. Bestia verto!"
Draco felt himself shrinking and he writhed frantically, trying to scream. The only thing that came out was a high-pitched squeak. He stared at his hands… they had been turned into paws. Draco was a ferret once more.
The ferret scurried out the door and quickly escaped Malfoy Manor. Harry turned to Brutus and inquired, "Should I fetch him back?"
The ancient Head of former Malfoy House chuckled and said, "No. He can discover the hippogriffs by himself. I do quite like Buckbeak; he has good taste in ferrets."