This is set during the third year of Hogwarts.
"Aren't you hungry Hermione?" Harry asked. "No, my stomach hurts." She said hugging her stomach. "Well, feel better soon." said Ron with a mouth full of toast and eggs. "Thanks Ron." She said sipping her pumpkin juice. Luna looked up from her issue of the quibbler, "Maybe you should go see Madame Pomfrey?" she said in her dreamy drone. "No, no I'm fine." She said nibbling gingerly on a piece of toast. "What do we have first period?" Harry asked still not entirely awake. "We have double potions with Slytherin." Said Hermione getting up from the bench. "I need to go get my stuff."
Hermione gathered her potions kit, her 3-foot long essay on sleeping draughts, and her brass scales. Hermione trotted down the stairs and towards the dungeons. It was still a bit early and no one else was in the classroom yet. She set up her cauldron, her scales, and got out her notes. She sat patiently on her stool. She winced slightly as her abdominal muscles tightened. Hermione brought her knees up onto her chair hoping to alleviate the ache and her stool wobbled ominously. She held her knees close to her savoring the few moments that the ache had disappeared.
The door leading to professor Snape's private potion stores opened quickly and slammed against the wall. "Whoa!" she cried falling of her chair and landing flat on her back. "Ouch." She said sitting up on her elbows. Snape looked at her from his desk and said rather icily, "Get up Miss Granger, I would prefer if we didn't have any accident s BEFORE class has even started, there are plenty enough with Mr. Longbottom in my class." He said turning his back on her to flick his wand at the blackboard. The day's instructions and assignment appeared on it and he sat down at his desk grading some papers from a Hufflepuff class.
Hermione bit her lip trying not to cry. She wondered why she was so easily upset, usually a remark from Snape like that wouldn't faze her in the least. She climbed back onto her stool and sat quietly trying not to draw attention to herself. Forgetting momentarily of her surroundings she sniffed quietly. Snape looked up at her briefly. He sighed heavily and put down his quill. "Miss Granger, please compose yourself or leave my classroom at once." He said with a look of irritation. She sat up very straight and swallowed back her tears.
Just then the rest of the class filed in noisily taking their seats. Chairs scraped against the stone floors. Metal clanged as students set up their scales and cauldrons. Harry and Ron sat down next to her dropping their bags at their feet. "Hermione, what's the matter?" Harry asked. "Nothing's the matter." She said quickly taking a deep breath holding her quill poised over her parchment. Harry and Ron exchanged looks and turned to their professor and glared quite briefly. So briefly it could have been mistaken for one scrunching their nose at the smell of the dragon dung from their potion kits.
"Today we will be starting on revival draughts. " he said "You will be making a rather simple one used typically on a fainted or un-conscious person." Said Professor Snape coolly. "You will all be needing ginger root extract which isn't provided in your potion kits, please come to the front of the class and you each need to take a piece of root, and please hand in your essays on sleeping draughts." He said sitting down at his desk once again to grade HufflePuff's papers.
Everyone handed in their essays, got their ginger, and began to work. The class went on as usual. Most of the class's potions looked pale orange and smelled of ginger. While Hermione had already passed the stage and her potion was clear and smelled of peppermint. She stirred counterclockwise six times and clockwise another six times. Done, she filled a small crystal vat with her potion and sealed it shut with wax. She began to clean up her cauldron when she felt something warm dribbling down her leg. She passed it off as a bead of sweat and continued to write. "Hermione your bleeding." Said Ron loudly. He pointed to the floor where a small pool of blood had appeared near her feet. Everyone heard and stopped what they were doing to look. She jumped out of her chair shocked beyond belief. "Sprung a leak, have we Granger?" Malfoy taunted. She ran out of the room blushing red and crying.
Everyone was silent. "Continue working." Barked Snape. He pointed his wand discreetly at the small puddle and it vanished leaving behind no trace. The class was silent except for the clink of vials and knives cutting on wooden blocks. Harry and Ron wanted to go and look for their friend but they could tell by the look on Snape's face if one more student interrupted his class things would not be pretty.
Finally class was dismissed and they went to look for Hermione. They tapped on the nearest Girl's bathroom door but no one answered and they were not going in there with a couple hundred students walking by. Harry and Ron reluctantly gave up and ran to their next class barely on time.
Professor had several more classes that day and they all seemed to be hell. A seventh year Ravenclaw had accidentally set another student on fire, a first year student accidentally cut off a small piece of his finger with a silver knife, and last but not least a mix up with potion elements had caused a small explosion in his fourth period class leaving several students without eyebrows. On his break period he received a notice from Dumbledore asking for him to come up to his office immediately. "Uh-Oh." He thought. "This cannot possibly be good."
He climbed the staircases to the seventh floor corridor where the giant gargoyle stood guard to the entrance of the Headmaster's office. "Licorice Wands." He said glumly. This day had seriously sucked. He climbed the stair case and knocked upon the great wooden door. "Enter." Came Dumbledore's voice. He stepped into the threshold. "You asked to see me headmaster?" he said. "Yes, please have a seat." Dumbledore said with a cordial wave of his hand. Severus sat down in one of the armchairs in front of the older man's desk. Phawkes the Phoenix whistled softly from his stand across the room.
Albus smiled. "This morning first period you had Hermione Granger in your class, correct?" he said. "Yes sir, Miss Granger was in my class today." Said Snape letting out a soft sigh. "You were the last one to see her today, she was absent from all of her classes and has not shown up at meals." Dumbledore stated matter-of-factly. "Was there not an incident, in the class today?" He asked rather calmly. "Yes, there was a bit of an incident." said Snape hoping to brush over the topic without having to go into detail. "Did she seem confused or scared, when she realized she had begun to menstruate. "Oh Great.'"Thought Snape. "I suppose so." He said curtly. "Well, if she doesn't understand what is happening to her someone should explain to her what is going on, we can't have her missing anymore classes." Said Dumbledore pushing his half moon spectacles up his long crooked nose. "You can't possibly mean…" said Snape in awe. "Oh but I do." said the older man. "Minerva has classes for the rest of the day, Poppy is busy tending to the accidents that occurred already in potions, Trelanway is well…Trelanway, Sinistra is out sick, and Professor Sprout is teaching her advanced herbology class how to prune venomous tentacula." He said standing. "You will have to inform her." He said with a seriousness one would not challenge. Severus stood and bowed his head, "Yes Headmaster." And with that he left the room.
He walked slowly down to the dungeons trying to think of what exactly to say and how. He went up to the women's lavatory and pushed open the door. He could hear the poor girl sniffling. He stepped into the room slowly. "Go Away!" he heard her snap loudly. He stood his ground firmly. Moaning Myrtle floated up out of a stall. "She said GO..oh hello Professor I will leave you to do what you came to do." And with that she quickly floated through the wall. "Miss Granger please come out of that stall immediately." There was silence. He heard the lock slide out of place and the hinges squeek. "Professor, what are you doing in here, this is the girls lavatory." She said wiping her eyes on her sleeve. "I was swnt to speak with you, since you haven't been in any of your classes. " he said with the most unreadable expression possible.
"What happened to you in class today is called a menstrual cycle or a period." He said. She watched him closely turning a violent shade of red. "It happens to young women around your age, and it will happen every month." He said. Snape felt color rise to his own cheeks. She wouldn't even look at him. "If you visit Madame Pomfrey she will provide you with necessary items for each of these cycles. " He said wringing his hands nervously. "So..its…normal for me to bleed out of my… "Yes." He said quickly cutting her off. Now clean yourself up and get to your next class." He said returning to his usual demeanor. Snape quickly strode out of the lavatory and back to the safety of his dungeons.
Harry and Ron quickly hid behind a tapestry. "Did Snape just come out of the girls bathroom?" Ron asked biting his lower lip trying not to burst out into laughter. "Yeah, I think so." Said Harry suppressing his laughter by biting his lip as well. When the echoing of his footsteps had stopped they ran for it up the stairs and back to the great hall to tell everyone what they had seen. And to this day, there is still the lingering rumor that Severus Snape is a transgender patient.