Disclaimer: These characters, settings, etc. do not belong to me in any way. They are the creations of J.K. Rowling. I am only using them for the fun and practice of writing.
Warning: Spoilers for the Half Blood Prince long about halfway through the book... Er... I suppose.
Ginny stepped through the wooden and glass threshold of the Herbology greenhouse, leaving the acrid smell of fresh potting soil and fertilizer for the sweeter smell of towering pines and gnarled oaks. Intently staring at her feet, she toed a few auburn leaves out of her path. And, hesitating for half a second, she kicked aside a twig before looking up to watch the crowd of fifth year Griffindors and Ravenclaws scurry across the grounds, keen to find shelter from the ever greying sky.
A sore thumb in the crowd, Luna stood stark still with her feet shoulder-width apart and school bag hanging precariously off her shoulder. Her bright blonde hair stirred slightly in the breeze. She grabbed a lock with her left hand and absentmindedly weaved it through the tips of her fingers.
Ginny moved quietly to stand by Luna's right side, gripping her own school bag tightly and gazing at the clouds. "Tut, tut," she said softly. "What with the rain and all." As a few cool drops fell from the sky, Ginny turned to look at Luna.
Luna smiled serenely, her radish earrings swaying slightly with the movement. "You know," she said, her tone confidential, "nargles hate rain." Brilliant blue eyes turned to look at Ginny with a wide-eyed, amused expression. "Something about an allergy to nitrogen."
Ginny cracked a small smile. "What's nitrogen?" she asked.
Bouncing on the balls of her feet, Luna answered airily, "Some kind of Muggle magic, I think."
The bag hanging off Luna's shoulder dropped to the moist ground with a soft and crumpled thud. Luna strode forward a few steps, swinging her arms from side to side in a sort of makeshift dance.
The rain began to fall harder, faster. Pulling her school bag from her shoulder, Ginny followed suit and threw it a meter or so to the side. She kicked off her shoes and tore off her socks. Pulling her robes to her knees and dancing, she swung her arms and shook her head as wet hair clung to her face.
Luna jumped into a newly formed puddle and clapped her hands together above her head. The pouring rain made her usually disheveled hair sleeker and at least three shades darker.
Lifting her chin to the sky, Ginny laughed out loud as one hand dropped half of her robes to touch her forehead and furrowed brow. Lightning streaked across the sky and thunder broke over them, reverberatingly.
"Get on to class you two," Hagrid's voice spoke over the last waves of the thunder.
She grinned, watching him wave a huge hand at them. "Sorry, Hagrid," she shouted over the pouring rain. Grabbing her belongings, Ginny tugged at the shoulder of Luna's robes and dashed for the nearest Hogwart's entrance. She stopped only to clean the mud from her feet and replace her socks and shoes, flashing a quick grin in Luna's direction.
"Maybe I'll see you after class," Luna said in an utterly unhurried manner. "I can't quite figure out today's Crumple-Horned Crossword."
"Sure. I'll see you later," Ginny said, hastily waving over her shoulder as she flew down the stairs at top speed. She entered the narrow corridors, her footsteps echoing and her school bag bouncing on her shoulder. She turned left. Still grinning from ear to ear, Ginny pulled her wet, ginger hair from her face and into a ponytail.
Carefully opening the door, she snuck quietly to her seat in the back of the class. Professor Slughorn turned to face her. "Ah yes, Miss Weasley. You're late," he stated casually.
"Er… trouble with nargles," she replied and bit her lip to keep from snickering.
"Of course, nasty devils," Slughorn nodded absently, ignoring a few giggles and snorts from the class. "Now, about the importance of dittany…"