Disclaimer: I don't own Harry Potter. Or even the idea of coming up with a Mary Sue parody. But I'm writing about both anyway.
Song: Headfirst for Halos by My Chemical Romance
MARY SUE COMMANDMENTS
I. Thou shall make thy Mary Sue have an extremely and exasperatingly long name that no one will care to remember.
Layla Jacqueline Ruby Tara Flora Autumn Brittnay Ilea Ebony Elizabeth Wren Opal Christina Linn Taylor Xanthe Harriet Marilyn Nadia Vera Diamond Karolina Johnson…
II. Thou shall make thy Mary Sue come from someplace other than Europe, like the Americas or Asia. And her family will be rich. Very, very rich.
…came from a very noble and rich family that completely dominated both the Americas and Asia at the same time with a gentle but firm hand…
III. Thou shall make thy Mary Sue insanely beautiful.
…her eyes, like glassy tears, shone in the different colors of the rainbow, and her hair, which brushed the ground but never got dirty, imperfect, or even greasy from a lack of washing, was as golden as the sun's rays but also as dark as a raven's wings…
IV. Thou shall make thy Mary Sue extremely modest, despite being a rich girl with insane beauty.
…Layla, however, never did like her family fame, fortune, or good looks. In fact, she was always so modest about them and even considered such things to be a curse! …
V. Thou shall make thy Mary Sue ridiculously powerful. Like, more powerful than Dumbledore.
…with one pale, beautiful hand, she could create a force field big enough to shield all three continents that her parents ruled over from any sorts of doom, and with her other pale, beautiful hand, she could fight whatever doom was coming down on her people…
VI. Thou shall make thy Mary Sue so ridiculously powerful that she was able to conceal her power until someone – usually Snape or McGonagall – accidentally stumbled on her using said power and ran to tell Dumbledore about not having this girl at Hogwarts.
…McGonagall said to herself as she picked up her skirts and ran all the way back to the Portkey, "I must tell Albus about this girl! She will make a formidable foe for Voldemort… possibly even more formidable than Harry Potter!"…
VII. Thou shall make thy Mary Sue about sixteen when either of the previously mentioned professors discovers her power.
…dropping to her knees, the barely-sixteen-year-old wept all the tears she could spare. "Now that woman will tell everyone about what a freak of nature I am!" she quietly wailed. "What am I to do now?"…
VIII. Thou shall make thy Mary Sue able and eager to enter Hogwarts, despite any previous evidence that should have prevented her from going.
…excitedly, she said, "Oh, it does not matter if I will be ridiculed! My feelings be spared; mother, father, I AM GOING TO HOGWARTS!"…
IX. Thou shall make thy Mary Sue be sorted into whatever House thou likes the best.
…"GRYFFINDOR!" the Sorting Hat screamed. Grinning and showing pearly white teeth, Layla flounced over to the Gryffindor table and made herself at home right next to the Golden Trio…
X. Thou shall make thy Mary Sue use any and all the slang she knows from her homeland, regardless of how she spoke in earlier chapters.
..."What's up, mah homies?" Layla asked the Trio eagerly. "Uh, wait, you Brits don't say that. Er… good day, govna!"…
XI. Thou shall make thy Mary Sue wear outlandish Muggle clothing that suits her style, despite the fact that in the wizarding world, people wear wizard clothing.
…and that day, she was wearing this absolutely beautiful black corset shirt with black silk ties, a plaid miniskirt that managed to make her look good instead of making her look like a slut, and these five-inch black heels that made her delicate frame rise to the height of all the other girls, who were wearing their drab robes again…
XII. Thou shall make thy Mary Sue captivate everyone, despite how out of character said everyone may get.
…"Marry me, darling!" a boy shouted from somewhere in the crowd.
Layla fluttered her long eyelashes as her pale cheeks turned a lovely rose pink. "I'm sorry, but I'm not in love with you," she called back to the boy shyly. "Maybe, if we could meet, I might get to know you better…"
"No, Layla! Marry me instead!"
"My love for you burns with white-hot passion, Layla!"
"Oh, Layla, the girls and I want to be your bestest friends ever! Do you want to come up to the dorm with us?"…
XIII. Thou shall make thy Mary Sue captivate even the fiercely canon characters already in relationships.
…Draco looked down at her intently, gray eyes teeming with iciness. "So," he said with a cold sneer, "this is the beautiful Layla Johnson that everyone is talking about."
Layla gulped, staring up at Draco Malfoy timidly and afraid to speak.
Then, without a word, Draco leaned down and kissed the beautiful girl full on the lips…
XIV. Thou shall make thy Mary Sue turn everyone out of character after a short period of time. Preferably a mere paragraph.
…Hermione flipped her hair over her shoulder and grinned devilishly at Layla, then at Ron. "Do you suppose he'll notice me now?"
Layla beamed. "Honey, he'll definitely notice you. If he doesn't, he's a complete and utter failure."
Replacing her grin with a confident smile, Hermione walked over to Ron, her hips swaying sexily. The redhead didn't stand a chance…
XV. Thou shall make thy Mary Sue face off with Voldemort.
…"Stupid girl!" Voldemort snarled, whipping out his wand and pointing it at Layla.
Layla, too, whipped out her wand. "Vile villain!" she cried…
XVI. Thou shall make thy Mary Sue win against Voldemort.
…everyone stared as Voldemort crumpled up into a heap on the ground. Then, everyone looked up at Layla and stared in awe…
XVII. Thou shall make thy Mary Sue die for no good reason other than it adds drama.
…putting a hand to her fragile heart, Layla cried out, "Oh, dear, I don't think that I can survive this terrible feat! Oh, my…!"
Everyone watched in horror as she, too, crumpled to the ground…
XVIII. Thou shall make thy Mary Sue come back to life in an extremely strange and clichéd manner.
…and Cedric Diggory, who had suddenly come back to life with Layla's death, leaned over Layla's dead body and kissed her on the lips…
XIX. Thou shall make thy Mary Sue die again and burn in hell because, frankly, no one reading the story wants her to live.
…"Oh my God!" Layla screeched as the flames of hell burned her. "Somebody help me!"
An evil voice cackled from the darkness. "You'll burn forever, dearie!" it said, then it cackled some more. "That's the fate of every girl who has the misfortune to be born as a Mary Sue!"
Layla screeched again…
XX. Thou shall smack thyself on thy head for even coming up with such a monstrosity in the first place.
Wow. That was a terrible parody. I ought to smack myself on the head for ever writing it in the first place. XD Oh, well.