He didn't notice her first year. Of course he didn't; she was eleven and he wasn't a monster.

Except that wasn't exactly true. Severus had noticed the Ravenclaw girl that first year, hadn't he? Not with any prurient interest but because she was noticeable.

The first time he noticed her was the first Quidditch game of the season. While every first year and most of the school was at the match, she was curled up in a window nook, book and quill in hand.

"What are you doing, Miss Stevenson? Why aren't you at the game?" he demanded, letting her know by his tone that he suspected she was up to no good.

She looked up and, inexplicably, smiled as if she was glad to see him. "Good afternoon, Professor. My parents sent me a book of anagrams." She held up the books. "I wanted to do some."

He raised his eyebrows. "Instead of being with your friends?"

She shrugged. "I don't really like sports."

"You're Muggle born. You've never even seen Quidditch played."

She sighed. "I suppose it's an experience, then. One I'll regret if I miss?" She sounded as if she were repeating something she'd heard many times before.

Severus was sorry he'd started the conversation. He had no real desire to make her go to the event. He'd only come over to make sure she wasn't plotting some mischief. He'd simply been point out facts.

"Your puzzles will still be there after the match. And… I suppose it is an experience. Your house is playing."

She sighed and closed her book. "Very well." She sounded resigned. With another sigh, she slid off the bench and stood next to him.

He frowned down at her.

She smiled sweetly. "Aren't you going too? We can walk together."

"You don't want to walk with me," he said harshly.

Her face fell. "Oh. All right." Head down, she started shuffling away.

Irritation rose in him. With a sigh and a roll of his eyes, he fell into step next to her.

Her face lit up and she reached out for his hand.

"No."

The girl nodded. With a happy expression, she and Severus walked to the Quidditch pitch together.

#

Fourth year, he paid her no mind until the day before they left for winter holidays. The holiday always put Severus in a foul mood, and this year was no different. Indeed, this year was somewhat worse. The weather was gloomy, but it wasn't quite cold enough to snow. Instead, it sleeted, and a grey slush was everywhere. He was cold, wet, and miserable.

So, when the girl made a mistake on her potion, he let loose with a torrent of insults. He called her a simple-minded fool, asked if her ears were stuffed with cotton, implied her birth was a result of an ill-advised match, and questioned her place at the school.

The girl just gazed up at him, expression somber. When he was done with her tirade, she nodded and said, "What must I do to get it right next time?"

"Try not to be an idiot," he snapped.

She looked as if she was suppressing a smile. "Of course. And besides that? What did I actually do wrong?"

"You don't know?"

She shook her head. "If I did, I wouldn't have messed up."

He gritted his teeth. "If you're really so interested in finding out, you can come back after supper and redo the lesson."

Inexplicably, her face lit up. "Thank you, Professor." Then, she gathered up her belongings and practically skipped out of the room.

He stared after her, flabbergasted.

"What a nutter," a student muttered.

"Who thanks a professor them detention?" another said.

"Mad Marissa, that's who."

Severus glared at them, angry that he was offended on her behalf. He hadn't officially given her detention, exactly. He'd been bluffing. He didn't want to spend the evening in the company of a fifteen-year-old girl. But, he'd dared her and she'd accepted. Now he had to go.

That night, after dinner, he went back to the classroom. The girl was already there, sitting on the flood, studying her potions textbook. When he walked up, she looked up at him and smiled.

"Thank you for letting me try again. I think I know what I did wrong but want to be sure."

"I won't change your grade if you get it right," he told her sourly.

Her smile faltered, but she nodded. "I understand. I guess it wouldn't be fair to change my grade and not give anyone else a chance. I'm not the only person who messed up. At least I have a chance to learn."

He looked at her incredulously. "Are you mocking me?"

She blinked, long golden eyelashes veiling her eyes for a moment. "No, Professor," she said, sounding astonished. "It's only that my father always says that failure is the first step on the road to success."

"Then your father is a fool."

She arched an eyebrow. "Then Edison didn't find hundreds of ways not to make a lightbulb only to eventually succeed?" Then she shook her head. "Oh, never mind. It's a Muggle thing."

He wanted to snap that he very well understood the reference but held his tongue. Instead, he opened the door and stalked inside.

She followed and took her usual place. Without a word, she unpacked her bag and started working. Severus ignored her and picked up a stack of scrolls to grade.

But, as the evening went on, it became harder to ignore her. First, she hummed as she chopped the ingredients. Second, she talked to herself as she measured, checking and rechecking her measurements against the book. Indeed, she would even say, "Check," when she was sure she was correct.

Then, there were her hands. While the rest of her was all awkward teen—oily hair and acne on her cheeks and forehead—her hands were sure and graceful. She wielded a knife as confidently and gracefully as a potions master would.

And, they were simply lovely. Long, graceful fingers. Clean, shined nails. Pale and well formed. He was hypnotized by them.

"Ah!" She looked up at him, beaming. "That's what I did. I was supposed to press the fava bean, not chop it. I only needed the juice."

He nodded before he could stop himself. "A silver knife is best."

"Is it? Thank you, Professor." Humming, she took a silver knife and pressed the bean under it, collecting the juice. "I also wasn't very precise when I was cutting today," she confessed, adding the juice to the potion. "Alice Creed told me that Trevor Bryce told her that Alec Mansfield said I was pretty. I guess that went to my head. Only last week, the boys were saying I was too ugly to ever be kissed."

Severus snorted. "Do you mistake me for someone who cares about teenage drama?"

She smiled. "Of course not, sir." She fell silent for a few moments before she said, "I'm done."

Reluctantly, he walked over to see. Waving his wand over the cauldron, he tested the integrity of the potion.

It was perfect.

He twisted his lips. "If you had done this in class today, you would have passed."

The girl beamed. "I did it right?"

"It's serviceable." He nodded. "Bottle it up and leave it on my desk."

She narrowed her eyes. "Why do you need it? It's not for a grade. It's a healing potion. What if I get hurt? What if a friend gets hurt? No." She began ladling the potion into the vial. "No, I think I'll keep this one."

He gaped at her a moment, then snapped his mouth shut. She was correct. There was no reason for her to leave it with him. He'd already said he wouldn't change her grade, even though the potion was of such high quality, she almost deserved it.

Almost.

"Very well. Clean up and remove yourself from the room. I have work to do."

She nodded and cleaned up. Even though she was clearly trying to hurry, she didn't rush. She thoroughly scrubbed her cauldron and washed her equipment. The, she scrubbed the surface of the table and carefully packed her belongings into her bag. When she was done, she stopped in front of his desk. "Thank you, Professor, for allowing me to fix my mistake. I am grateful."

He hummed noncommittally. Then, he looked up at her. "Don't let your mind wander in class again. You won't have a second chance every time."

"Of course not, Professor." She smiled and there seemed to be a secret clinging to the edges of her lips. Then she left.

#

By her fifth year, it had become a habit and she was impossible to ignore. She was constantly in the class outside of school hours. Any time her potion failed, she would turn her large hazel eyes on him and ask if she could come after dinner and try again.

He didn't know how to say no. There was no ready excuse. He spent the evenings in his classroom grading papers and presiding over detentions. Everyone knew he was there. She was the only one who took advantage of it.

The problem was, she began coming even when she hadn't made a mistake on potions. She came in to work ahead or brew from book she got from the library. She brewed, humming softly to herself, chopping and measuring, elegant hands moving with growing precision.

She would rebrew potions, too, trying different methods of preparing the ingredients. Soon, she was brewing master-level potions. Snape had no choice but to give her the highest marks. She'd begun to earn them the first time.

"Professor?" she said one night, looking up from her cauldron.

"What?" He continued grading, slashing red marks through abysmal drivel.

"I was wondering. Anti-poison potions are wonderful, but what if someone poisoned and one doesn't have any near? Is there any way to save them without a potion?"

He let out a snort and marked the next page. "Why do you persist in trying to make me do your thinking for you?"

"You're a teacher. Isn't it your job to give me answers?"

He carefully set down his pen and looked up.

She had her chin propped on her fist and was gazing at him with a small smile. Her eyelashes were ridiculously long, and he felt his anger stir.

"It is my job to make you think. To give you the tools to find the answer yourself. If I told you, then you would have learned nothing."

She raised her eyebrow. "Then how do I learn if not go to you?"

"Try the library," he said dismissively. He looked down at his grading again.

"Hmm. Good idea."

He glanced up to see she'd gone back to brewing. "What are you doing tonight?" he said, nose twitching from the smell.

"Skele-grow."

"Why on earth would you need Skele-grow? What are you planning, girl?"

"Nothing!" She laughed. "I don't need it for anything. I just thought it looked challenging." She finished crushing the scarab beetles and added them to her cauldron. "I've heard it tastes awful. I tried to find a way to make it taste better, but it seems like everything reacts badly."

"How did you test? Where did you test?" He disliked the idea she was brewing potions out of his sight. Not that she needed supervision, per say, but it sat badly with him.

She shook her head. "I didn't test. I ran through the ingredients and looked for possible interactions. Every single flavoring I could think of reacted with each least one of the ingredients. It was very irritating."

"You… You figured that out from research?" Despite himself, he felt a stirring of admiration. Damn if he'd let her know. He set his quill down and rose.

She stopped stirring and looked up at him.

He ran his wand over the cauldron.

The position was good. Medical students didn't learn how to brew it until the third year of their apprenticeship. Snape had learned it the end of the second year of his. She was fifth year.

He forced his face into a mask of indifference. While Slughorn had spent his career fawning over students and vying for their attention, Severus would never stoop so low. Consequently, Marissa Stevenson would never know she was his most gifted student, at least not from him.

"What are you career plans?" he asked abruptly, putting away his wand.

She pursed her lips. "I'm torn. On the one hand, I love potions and wouldn't mind pursuing a career in it. However, recently, I've been reading about curse-breaking. It sounds so intriguing. I've always loved puzzles and riddles. Curse breaking would be like solving them for a living."

"So, you seek fame and fortune."

She waved her a hand and rolled her eyes. "Not that I'd turn down either, it's not my main goal. It just seems like a profession where I'd really get to use my mind."

He was skeptical of her response. He'd never met a teenager who didn't want fame and fortune. But, instead of challenging her, he merely said, "Curse-breaking is a notoriously difficult profession for Muggle-borns to break in to. If you aren't hired by Gringotts, that is. Most of the major curse-breaking firms are run by old Pureblood families who can be quite prejudice."

Her face fell. "Is that true?"

"Am I in the habit of lying to you?"

Her lashes veiled her eyes. She picked up a vial and began ladling potion into it. After a long moment, she shrugged. "I've always liked a challenge."

He exhaled sharply. "You are impossible, child."

#

Two days later, at the end of class, she stopped in front of his desk as the rest of the students filed out.

"What?" he snapped. Four students had exploded their cauldrons and he had a headache from the terrible weather.

She smiled. "Bezoars."

He closed his eyes and pinched the bridge of his nose. "What are you blathering on about, girl?"

"If you don't have an antidote to a poison, you can use a bezoar. They work for almost everything." She beamed.

Severus let out a sharp huff. "Do you want a medal?"

She laughed. "I'll see you tonight, Professor."

"Oohh," Pamela Trunchbull said mockingly. She exited the room, but not before Severus heard her say, "Stevenson's got it hot for the greasy old potion's professor."

"Fuck off, Trunchbull," the girl said, voice light and breezy.

"Ten points from Ravenclaw for language." But that wasn't really why he took the points.

#

To no one's surprise, least of all Severus's, Marissa Stevenson got an Outstanding on her OWLS.

#

Sixth year, she began dating a boy. Snape took no notice. How she managed to date, continue experimenting with potions in the evening and suddenly become top of her class in Potions and Ancient Runes, with more than passable grades in Arithmancy and Defense Against the Dark Arts, he didn't know. Nor did he care.

It was a long year.

#

"Professor."

"What?" he snapped, not looking up. He was preparing a potion for sixth year to deconstruct. Last week, seventh year had done a similar lesson with a much more complicated potion. He had banned her from the classroom for a week while he prepared the potion, not wanting to give her any advantage.

She'd passed anyway, then admitted that she's brewed the potion before. Consequently, he was preparing a relatively new and very advanced potion called Wolfsbane for her to deconstruct. If she was able to break it down, he'd be very surprised.

"What do you think the ethical implications of brewing Amortentia are?"

He looked up. "Don't you have more important things to do right now?" He wasn't testing her at the moment, but she'd been working out of his old master's brewing textbook for weeks. He'd told her he'd write a letter of recommendation to the master he'd studied under if she could brew even half the potions.

She waved a hand over her cauldron. "I'm waiting for it to boil. What do you think?"

"I think anyone who uses Amortentia is a fool."

"I agree." She shook her head. "But is the brewer a fool? And, beyond that, would I be unethical?"

"How so?" He set down his paring knife.

"I know love potions don't invoke real love, but they do alter emotional state and induce euphoria while lowering inhibitions. They take away your ability to think clearly and rely on deceit. It just seems wrong."

He tilted his head. "A potion in and of itself is neither evil nor good. I assume you aren't using it, unless your boyfriend has lost his passion for you."

She blinked, looking surprised. "I haven't a boyfriend. Oh. Oh, no. Charlie and I broke up when he left school last summer. This isn't for me. Some of the students have been asking me to make it for them."

He felt nothing on hearing that she was no longer attached to the Gryffindor boy. That would be beyond inappropriate. It would be obscene. She was, after all, seventeen years old. He was her professor.

He felt nothing.

"Only a fool would brew a potion in exchange for nothing," he gritted out.

Her eyes lit and a smile curved her mouth. "Why, Professor. Surely you are not encouraging a student to charge other students in exchange for a service."

"Encouraging, no. Stating a fact, yes."

She wrinkled her nose, a delighted look on her face. "I see. Well," she said coyly, looking through her lashes, "it's lucky I am not a fool. Nor have I been for some time."

Ah. That explained the unusually clear complexions and luxurious hair amongst the seventh year Ravenclaw girls this year. He had wondered.

He tilted his head. "Surely those asking don't have a nefarious purpose in mind. They merely want to be close to the object of their affection."

She sighed. "Yes, except… well, a Slytherin boy asked and requested I make it extra strong. He also asked if I could include a memory altering charm."

"Which boy?"

"Professor, I must protect my clients."

He tightened his fist around his scalpel. Unfortunately, he grabbed the wrong end, and the blade dug into his finger. "You do understand what he is planning."

"I'm not entirely naïve," she said dryly. "I thought about giving him a defective product, but my pride won't allow it." She frowned and wrinkled her nose. "I think I'll just refuse to brew it for anyone. It doesn't sit comfortably with me. If people want to be with someone, they should do it naturally."

"Like you and your boyfriend. Oh, sorry. Ex."

She rolled her eyes. "Actually, I used a love potion on him to get him to notice me."

He tightened his hand again. "I'm appalled."

"And I'm joking. I… Professor, you're bleeding." She came around from her table and approached him.

Severus dropped the scalpel. "I assure you, it's nothing."

She caught his hand before he could take it away. "Silly man," she said, running her wand over the wound.

With a cool tingle, the skin knitted leaving only blood behind. "It was an accident."

"Clearly. I can't imagine you'd ever be stupid enough to injure yourself on purpose." She looked up at him, humor lighting her eyes and a smile curving her mouth. She hadn't let go of his hand.

She hadn't let go of his hand.

A hot flush heated his neck. He snatched his hand away. "Your potion is boiling."

She looked at him for another long moment, then sighed and went back to her station. "He's a sixth year," she said as she began adding the next ingredient. "Black hair. Blue eyes. Tall. Why he needs a love potion is beyond me. He could probably have any girl he wants."

He cleared his throat. And then cleared it again. "That's the type that's the most dangerous. Because there's always someone who doesn't, and then it's a challenge." He swallowed. "I'll take care of it." Then, because he was a professor and she was a student, he added, "And stop selling potions to your classmates. It's against the rules."

Without looking at him, she smiled that secret smile and said, "Of course, Professor."

#

Suddenly, there were illicit potions everywhere. Every student had one, in ever year, every house. With her earnings, Marissa Stevenson managed to acquire a new cauldron, an apprentice potion kid, and a new preparation kit. One of the highest quality. In fact, it was better than Severus'.

She was discreet, too. No one could catch her at sales. He didn't try, but other teachers did. Everyone knew it must be her because no one else would have anything nearly as high quality. While it caused great consternation in the teacher's room, Severus didn't give much thought to it. Students were always illicitly selling something; they'd done it when he was in school, they did it now, and they'd do it in the future. If they put out a good product and didn't get caught, who was he to complain?

Until they day he caught her in the middle of a sale. It was completely accidental. He'd been going to the Owlery to mail something off when he'd stumbled upon her mid transaction.

The student who was buying the potion was quick. She was Slytherin. Without a word, she dropped the potion and fled before Severus had even gotten a proper look at her.

Marissa Stevenson was left with a broken potion bottle at her feet, a few Galleons in her hands, and a sheepish expression on her face.

He let out a short huff. "Two weeks detention."

"That's hardly a…"

"You are banned from my classroom after hours for two weeks. Not one foot, not one excuse. I don't want to see you." He strode past her in a flurry of robes.

"Because I was selling or because I was caught, Professor?" she called after him.

Luckily his back was to her. It wouldn't do for her to see the twitch in his mouth at her impertinence.

And, yet, he never saw it coming. When it happened, he was blindsided.

It was happened the afternoon of the Leaving Feast. It was the usual celebration and high spirits, with those leaving the school for good slightly maudlin at times. It was loud, it was chaotic, and it was overwhelming.

Severus left the first moment he was able, slipping away to his classroom to finish setting his classroom to rights before he left. He'd only been there a few moments before he heard the door open.

"Professor."

He turned. "Miss Stevenson. What are you doing here? Shouldn't you be with your fellows getting in your final moments?"

She rolled her eyes and waved a hand. "The ones I'm friends with, I'll see again. The rest…" She shrugged. "I'm sure I'll see around somewhere." She took a step closer.

"What are your plans for the summer?"

"Egypt. Gringotts has accepted me into their curse-breaking program. I leave next week."

He twisted his lips into a frown. "Fame and fortune."

"I'd rather curse break for a firm, but no one would take me on. At least this way I'll have experience."

Severus went to his desk and pulled out an envelope. "If you ever reconsider, here's the letter I promised you. The man I studied under is very good and while he's harsh, he's not prejudiced. He stood with Muggle-borns when during the war."

She seemed to float across the room. Her fingers brushed his when she took the letter. "Thank you, Professor Snape. I will keep it in mind if my chosen field doesn't work out." She licked her lips. "Professor." She stopped talking.

"Yes?"

"I…" For once, she seemed at a loss for words. She frowned, a winkle appearing between her eyes. "I wanted to say…" She shook her head. "I mean…"

"If you thank me…"

"No," she said, laughter fluttering her words. "Not that. It's simply… Oh." A determined look came over her face.

Before he knew what she intended to do, she stepped into his space and pressed her lips to his.

Panic welled in him. He pushed her away perhaps a tad too violently.

She stumbled back and caught herself against a table. "Sev…"

"No." He shook his head vehemently. "No, I can't. I don't…"

The girl blinked up at him, that determined look still on her face. "Don't be stupid. We get along. We have similar interests. We enjoy each other's company. I'm no longer your student. So why…"

"I'm much older than you."

"By, what? Thirteen years? What does that matter? We're both adults."

"You are a child."

She tightened her jaw. "Not according to the law."

"You are my student."

"No. I'm done with school." She took a deep breath and stepped forward. "I come back at Christmas. Perhaps we can get a cup of tea."

"Child…"

"My name is Marissa."

He closed his eyes. "Marissa." He let out a sharp breath. "What you ask is impossible."

"Why?"

"It just is."

There was silence. He clenched his fists and listened to himself breathe. The back of his neck was hot, and it prickled. His mouth still tingled from the brush of her lips.

Finally, she sighed. "Very well. I'll leave it be." He heard her soft footsteps on the stone as she must have walked away. Then, they stopped. "At least for now."

His eyes snapped open.

She was giving him a sweetly mischievous smile. "This isn't the last we'll see of each other. And I've always liked a challenge."

"Marissa…"

"Good-bye, Severus. Take care." Then, before he could say anything else, she slipped away leaving him alone, flustered, and completely confused.