A little story inspired by a discussion on the Harry Potter subreddit, about whether Fiendfyre and the flame monsters it conjures are the Dark equivalents of the Patronus charm - and if so, do you need a really bad memory to cast it?
"Now, Draco," Lucius said with his friendliest sneer plastered on his pale face. "Focus your mind, and bring up your worst memory, the least pleasant experience you've ever had, and then cast the spell."
The young peroxide-bleached neophyte Death Eater matched his father's sneer, staring into mid-air for a moment, before raising his wand.
"Mendax mendax braccae exussum!" he shrieked, roiling hellfire spewing from the tip of the hawthorn wand. Lucius spared him a congratulatory smirk.
"Well done," the elder Malfoy said. "Although, I am quite curious - which memory did you choose?"
Draco stood silently, averting his eyes while twirling his wand nervously.
"You see," Lucius drawled and stroked his pointed chin, while inspecting the fiery Dark magic that was currently consuming a Muggle trash can like the youngest Weasley boy mowing through a buffet table. "I've never before seen Fiendfyre take the shape of a ferret stuffed inside something that looks like... a pair of trousers?"
