Severus was sitting in a chair by the fireplace, hands steepled, legs crossed, deep in thought, when his apprentice returned from teaching the first year Hufflepuff/Slytherin class. Hermione slammed into the room, not noticing him off to the side, and immediately ripped off her teaching robe and flung it across the room.
"Bugger! Bugger, bugger, bugger!"
Severus snorted, causing her to whirl around in surprise, then said, "I hate teaching the Huffs and the Slytherins at the same time, as well. Minerva must have been Confunded when she made the schedule, or else she has a cruel sense of humor."
A tiny giggle escaped from Hermione's pursed lips, and her wretched mood evaporated as she smiled at her mentor. She was wearing an old, strappy sundress that she often wore under her robes during the late-Spring months. The castle never got hot per se, but there was a mugginess, especially in the dungeons with 20 students brewing simultaneously. The stone walls would sweat with humidity, and her hair would curl into damp corkscrews around her face. Severus found this secretly enchanting, but his expression grew dark as he noticed her attire. "I thought I forbade you to wear that garment."
"It's just a dress, Severus, honestly! I wear far less to a public beach." Hermione fingered the faded blue cotton material, rolling her eyes. Pointedly turning her back on him, she began to fix herself a cup of tea from the nearby tray.
"It is no matter to me what libidinous costume you tart yourself up in whilst on vacation," Hermione gasped angrily, but he continued, "as my apprentice, you will abide by a modest dress code..." At this point, he was interrupted by said apprentice peeling off and flinging the offending garment directly into his startled face.
Time stopped. Silence reigned. Hermione stood clad only in pink bra, boy shorts and sensible thick-soled dragon-hide boots. Severus sat straight in his chair as the dress slid down his face onto his lap. A deep, red flush was traveling down his apprentice's face and neck, and her chest heaved, yet her eyes remained defiant.
"You are playing a very dangerous game, Granger. Are you sure you know what you're doing?" His obsidian eyes were unreadable as they leisurely traveled from her defiant eyes down to the toes of her boots and back up again. "I will not be teased."
When his eyes met hers again, she purred, "Would I do that, Severus?" She sauntered a few paces closer to his chair, arms away from her sides like a tightrope walker, fingers feeling the air which tingled with magic and something else. Hermione looked deeply into his eyes and whispered, "Would I tease a deadly snake, Severus? Me?" Three more paces, she was closer, smiling mysteriously. He did not move a muscle. Two more paces and she'd be in touching distance. "Would I tickle a dragon, Severus? Would I poke a hippogriff?" Two paces and she was leaning over him.
His brain was addled. Granger had him completely bewildered. Perhaps it was a Polyjuiced imposter? Imperius? Perhaps he was dreaming, otherwise, why was his delectable apprentice standing over him in her skivvies, purring like an erotic kitten? He needed to take charge of this situation, and fast.
Wordlessly Summoning his wand, he was about to throw a Petrificus when he realized his wand hadn't smacked into his palm as usual. He tore his eyes away from Hermione to look for it, missing the triumphant look that crossed her face as she scampered backwards toward the door -- holding his wand.
Without thought, he was up facing her. "What are you playing at, Granger?" He watched in horror as she twisted his wand into her hair and poked it into a bun, and again he tried to Summon it, but she had put a heavy-duty Sticking charm on it. She was giggling and weaving back and forth, deciding which way to run should he charge her.
The magic and tension in the room collided and supercharged the air around them. Hermione edged to the doorknob and turned it. "I think I'll just run up to the Great Hall."
"Don't. You. Dare."
"Don't you dare, Severus! I've had enough of your lectures on proper behavior. I'm going to run to the Great Hall in my underpants and announce that I got your wand away while you were staring at my tits!"
Hermione felt like she had lost her mind and knew she looked quite deranged, half-nude with a wand stuck to her head; however, she really had reached the end of her rope with the damned students today, added to the year and a half of unrequited sexual tension with this blasted, gorgeous man.
She giggled madly and ran out the door.
Darting into the hallway in pursuit, Severus felt like he was in some strange, yet titillating, dream. He was chasing his scantily-clad apprentice through the dungeons. That just did not sound like something which would ever happen to him, really. At least not outside of recent moments of solitary fantasy.
Hermione had aroused him, disarmed him, yelled at him, and now she was running around with his wand where anyone could see her. He'd be a laughingstock if word got out he couldn't control his apprentice. Students would need Obliviating. He simply had to catch her, quickly and quietly.
Three corridors away behind a tapestry, Hermione was coming to her senses. Severus was going to kill her. Even if he didn't, there would be maiming and even worse, she would lose her apprenticeship. All of her hard work, all of the late nights testing potions, grading parchments, writing out her research, all gone because she had a bad day, and he just had to say something about that stupid blue sundress. On top of it, she was insanely aroused and having a blast being chased by Severus.
"Gods, what is WRONG with me?" she thought. "I'm going to apologize."
As soon as Hermione stepped out from behind the tapestry, a strong arm banded around her waist and lifted her up. She squealed and struggled, and Severus grunted from the strain of containing her ample form. "Give it up, Hermione, your moment of punishment has arrived!"
Hermione used the only fail-safe trick in her arsenal, learned from long summers in her youth spent wrestling her cousins; she jammed a hand deep into his armpit and tickled. Her world flipped as he almost dropped her and only just managed to catch one leg and a shoulder, leaving her swinging, head down.
Not wanting to waste any advantage, Hermione clamped her fingers into his sides and continued tickling mercilessly. His sudden rich, dark, hysterical laughter delighted her so much that she forgot to be scared for a moment and started laughing too. Helplessly, Severus scrambled to hold her one-handed while seeking to remove the tickling hands from his waist and ribs. He almost dropped her again, but managed to remove her hands and face her outward, still upside down, with her legs over his shoulder.
At that moment, Minerva McGonagall came around the corner and stopped dead in her tracks.
It was an excruciating few moments. He set Hermione roughly onto her feet and stood silently, glaring. Hermione was stuttering incoherently and blushing crimson and bolted gratefully when Minerva dismissed her to get dressed. Severus straightened his robes and tried to regain some poise, but it was difficult with Minerva squalling in his face.
"I had several hysterical students come tearing into my office saying they heard you laughing in the dungeons. They were terrified out of their wits!"
He sniffed. "There was a minor disagreement between my apprentice and myself regarding dress code. Nothing to concern yourself with, Minerva."
It was several more long minutes of giving one-word answers to Minerva's questions and railings about propriety before she buggered off down the corridor. She seemed suspiciously unfazed by the fact that Severus had been wrestling with his half-nude apprentice, only that it had occurred in public. He'd file that peculiar tidbit away to think about later. He had bigger hippogriffs to grill right now.
Head down, brow cloudy, he stomped into his quarters to see Hermione fully dressed in a modest long-sleeved dress, standing nervously next to the credenza. His wand lay neatly atop a pile of books nearby.
He picked it up and advanced on her. She closed her eyes, mutely accepting whatever her punishment would be. They snapped back open when he lifted her up and set her down hard on the credenza. He jerked her knees apart, settled himself between them and pulled her close, eye to eye, noses touching. Breathing erratically, they simply stared until he seemed satisfied with what he saw and leaned in with a rough, searing kiss.
A moment later he broke away, whispering, "I'm going to have to ask you to take a wand oath never to reveal that I'm ticklish."