After a restless few hours sleep, Minerva had dragged herself out of her bed to take her first lesson of the academic year. Normally she would have been extra vigilant in a classroom full of sixth year Slytherins and Gryffindors, but she was too distracted even to notice when Sirius Black, in a humorous effort to turn James Potter's hair green, had accidentally vanished it completely. Rapturous laughter rang throughout the classroom as James shouted at Sirius, who was running around the classroom dodging missiles launched by his furious best friend.

It was most unlike her to be so distracted, but her thoughts kept returning to John Constantine time and time again. She remembered him well during his school days, he had been one of the most talented and frustrating students she had ever happened across. A naturally gifted wizard, no spell or potion ever presented a challenge to him. Perhaps that was part of the problem, she realised - he must have found school incredibly boring. It would explain why he had acted out so often - performing dangerous experiments in empty classrooms, going on excursions to the Forbidden Forest simply because he was told that it wasn't allowed. Skipping lessons, getting into fights with other students...Merlin, she lost count the number of times she had given him detention for smoking in the corridors.

It hadn't come as much of a surprise when John hadn't returned for his seventh and final year at Hogwarts. He'd left at the first opportunity, and nobody had seen or heard from him since. Which is what made his sudden return after a six-year absence all the more curious to Minerva. What in Merlin's beard was he doing back at a school that he had been so desperate to leave in the first place? And what had possessed Dumbledore to take him at his word and hire him?

Well, she knew Dumbledore believed that good lies in everyone and that second chances could reveal the best in people. He was a generous man - too generous, sometimes - she would have been more reluctant to welcome the reckless former student back into the fold, however talented he was. She mulled over Dumbledore's words from the previous evening - would she have been as harsh on John if he had been a Gryffindor? She glanced up at James and Sirius, running around the classroom and sighed: no, she probably wouldn't have.

Maybe she should take a leaf out of Dumbledore's book and give the boy a chance. It had been six years since she had last seen or spoken to him. Then again, Dumbledore had asked her to keep tabs on John's behaviour; clearly, he wasn't completely blind to what he was capable of. Still, John had been in the castle for a few hours now and nothing untoward had happened - yet.

Minerva pulled a blank piece of parchment towards her and began to scribble down notes, oblivious to the chaos that reigned all around her. She found writing lists helped reduce her anxiety; it had been a coping mechanism she had picked up during her own school days and it had stuck with her ever since. She wanted to have a clear idea of what she was going to say to John, resolving to meet him after morning lessons had concluded. Thankfully, the students were too busy fooling around to take any notice of her, so she could write in relative peace. Well, most of them...

"Professor, I've completed today's task."

"Hmm?" Minerva looked up from her desk to find a stringy, pallid-looking boy looking expectantly at her.

"I've completed today's task," he repeated. "May I be excused from class early to go to the library?"

Minerva frowned at him, "You may leave, Mr. Snape, after you demonstrate to me what you have learned."

Severus Snape drew his wand, pointed it at his own head and said, "Crinus Muto."

In the blink of an eye his black shoulder-length hair became several shades lighter as it began to recede into his scalp. Within seconds his hair had transformed completely, no longer a dark curtain of greasy black hair, but short and sandy-blonde. Minerva fleetingly thought that it reminded her of John's hair, but she quickly pushed that inappropriate comparison from her mind and gave Severus a curt nod.

"Very well, Mr. Snape, you may gather your things and spend the rest of the hour in the library."

Severus tapped his wand to the side of his head and his hair turned back to normal. He quickly gathered his things and hurried for the classroom door, but not before Sirius shouted after him, "At least you still look better than Snivellus, James. Anything's better than that greasy mess on top of his head."

Severus ignored the chorus of laughter that followed him out of the classroom, slamming the door hard behind him without bothering to respond to the jibe. Minerva turned back to her notes and began scribbling again.

"Perhaps if you spent more time learning the spellwork instead of making witless remarks like that, Mr. Black, then you would also be permitted to leave the classroom early," she pointed out.

She could practically feel Sirius' eyes roll, but he knew better than to respond. She might have a soft spot for the boy, but she wasn't adverse to handing out detentions if he kept pushing his luck. She looked over her notes again and nodded to herself in satisfaction. She and John both had a free period after lunch; she would meet him in the Great Hall, then head back to her office for a much-needed chat.

John didn't come to the Great Hall for lunch that afternoon. In fact, from what the other staff members were saying, nobody had seen him since his dramatic arrival the night before.

"He didn't even turn up to his first lesson this morning," Slughorn informed her quietly so as not to be overheard.

"What?" she hissed incredulously. Slughorn nodded mournfully.

"Binns was passing through the classroom when he found the students all sitting there, still waiting for John to turn up," he sighed. "If he keeps that up, Dumbledore will sack him, for sure. It's a shame, really: I was hoping that he would at least last until the end of the week - I was sure I was in with a good shot of winning the dead pool this year..."

Minerva's fork clattered onto her plate and she sprang to her feet. She had foolishly been considering forgiving John of all of his previous transgressions, had let herself hope that they could start things on a clean slate. But failing to turn up to his own classes on the first day...it was unforgivable in her eyes. Notes and composure all but forgotten, she strode from the Great Hall like a woman possessed, straight for his office.

When she reached his office on the second floor, she didn't even bother knocking before entering. Throwing the door open she stepped inside, scanning the messy room for the absentee professor. Several cardboard boxes lay unopened across the otherwise bare office space. The only area which had been set up was the large writing desk at the back of the room in which John's essential had been put in pride of place - an ashtray overflowing the cigarette butts, a half-empty bottle of Ogden's Firewhisky, and a Muggle magazine with Rolling Stone written on the front cover. No books. No teaching equipment. Just booze and cigarettes.

"Bloody typical," she muttered, drawing her wand. She marched towards the sleeping quarters, knowing fine well what she would find. Banging on the door to the bedroom, she bellowed, "John Constantine! You come out here this instant!"

She didn't care if John was now one of her peers, she couldn't help but speak to him like he was still one of her students. She banged her fist against the door again then paused when she heard a muffled voice call out.

"Alright! Alright, I'm coming. Keep your bloody shirt on..."

The bedroom door creaked open and a bleary, bloodshot eye peered out at her. The piercing blue eye widened in surprise as he recognised his visitor and the door opened fully to reveal his disheveled appearance. His five o'clock shadow aged his handsome features, but the cheeky grin spreading across his face made him look like a mischievous schoolboy.

"Minnie!" he said cheerfully. "It's great to see you again, love. It's been a while...what are you doing here at this hour?"

It took Minerva a few seconds to process everything in that single sentence that incensed her before she could respond. Her eyes narrowed and she spoke as calmly as possible through clenched teeth.

"It is the afternoon, John, and you will address me as Minerva or preferably, Professor McGonagall. And it may have escaped your notice but today is the first day of the new term; you missed your own lessons this morning. But given the state you're in..." she looked him up and down, naked except for a pair of form-fitting boxers and drew him a disparaging look. "Perhaps it was better the students didn't see you today."

Or ever, she thought darkly.

"Is it?" he asked unconcernedly. He ran a hand through his thick, sandy-blonde hair making it stick out in all directions. "Bugger, I thought tomorrow was Monday."

"Perhaps I should transfigure you into a calendar, then. That way, you might keep better track of your schedule," she snipped. Instead of looking appropriately bashful, John grinned.

"You might be onto something there. I'll uh...be out to see you in a couple minutes, yeah? Just need to get dressed..."

John closed the door on Minerva's furious face, reappearing a few minutes later wearing a wrinkled white shirt and brown suit. Minerva stood by the small chair in front of his desk, her dark eyes following him as he shuffled into the office. He fumbled with a plain burgundy tie before sinking into the seat behind his desk.

"Drink?" he asked, nodding towards the bottle of Firewhisky. Minerva's nostrils flared.

"No," she replied shortly. John shrugged and proceeded to pour himself a sizeable measure into a crystal tumbler that he conjured from thin air. She opened her mouth to comment on it being too early to drink, and instead gaped in horror as another figure slipped out of John's bedroom; a dark-haired girl in a party dress tried and failed to tip-toe unseen out of the office. She gave John a slight wave goodbye, then immediately lowered her hand and bowed her head as she met Minerva's incredulous gaze. As the door to the office slammed shut, Minerva glowered at John.

"Who..." she hissed, accenting each word. "Was that?"

John shrugged, "Someone I met down the pub last night, I reckon."

"You can't even remember?" she asked, horrified.

"I had a lot to drink last night," he acknowledged, taking a swig from his tumbler and grimacing at the taste. Minerva scrunched her nose in disgust.

"And that is going to help?" she asked sarcastically.

"Probably not," he admitted, slamming the tumbler down on the desk. He flashed her a toothy grin and leaned back in his swivel chair, "So, how can I be of assistance to you? Doxy's in the office you need seeing to?"

Minerva fixed him with a steely gaze. His relaxed demeanour only irritated her more.

"I want to know what you're doing here at this school," she challenged. John chuckled.

"No mess tins with you, eh Minnie? Always straight to the point."

"Professor McGonagall," she corrected him again sharply. "And you know me well enough that I always prefer to be direct, so let us be direct with one another."

John stretched back in his swivel chair and rested his arms carelessly over his head, "Okay. Fire away."

Minerva rose herself to her full height before she declared, "You are an arrogant, reckless show-off. You shirk the rules because you believe that they are beneath you, and have always been more concerned with proving how clever you are than following instructions; school property and student's safety be damned. I don't approve of you being here, and I think your appointment will be a detriment to this school and its students."

Hurt streaked across John's face, but he quickly covered it with a cheeky smile and a retort, "Streuth! You really like to go for the jugular, don't you? Please, tell me how you really feel about me..."

"You obviously have no interest in teaching," she said accusingly. "Otherwise you'd have the decency to at least turn up to this morning's classes instead of sitting here half-cut reading Rolling Stone magazine." John quickly stuffed the magazine into the top drawer of his desk out of sight, then proceeded to pour himself another drink. Minerva continued, unperturbed, "And from what I do know of you, you never did anything for anyone unless it benefitted you in some shape or form. So clearly you stand to gain something from taking this job. Whatever it is, it can't be the money. Believe me, I know how little you're getting paid. So, I want to know what it is that brought you here."

"Why?" he asked roughly, all pretense of a smile and charm gone now. Minerva glowered at him.

"Because the sooner you get what you're after, the sooner you'll be out of this school."

John considered her in silence for a few moments, perhaps trying to decide how honest to be with her. Finally, he shrugged and said, "Okay, you got me. There is something I want and I can only get it here at Hogwarts and nowhere else."

Minerva waited with baited breath, "Well...what is it?"

"Knowledge," he replied simply. When McGonagall gave him a withering look he rolled his eyes and explained, "The library has books that you can't find anywhere else in the Muggle or Wizarding world. I asked Dumbledore for the job but I only agreed to take it on the condition that I had unrestricted access to the books in the library and the works he keeps in his private collection."

"What type of books are you looking for?" she asked curiously. "What branch of magic?"

"Dark ones," he replied mysteriously, wiggling his eyebrows. "Dangerous ones."

"For what purpose?" she pressed on. John gave a hollow laugh.

"Believe me, you're better not knowing," he warned, snatching the packet of cigarettes off of his desk. "You still smoke?"

"I quit."

John shrugged and flipped the lid open, then frowned when he realised that the packet was empty.

"You just don't want to tell me because you know I won't approve," she argued.

"An astute observation," he replied distractedly, patting himself down, looking for something. He opened the top drawer of his desk and exclaimed, "Ah-ha!" before pulling out his wand. He raised it into the air and cried, "Accio Silk Cut."

A packet of cigarettes flew out of a rucksack from the corner of the room and soared through the air towards John's outstretched hand. Before John could reach them, however, Minerva caught the packet, held it at arm's length and drew her own wand.

"Incendio," she muttered. John cried out angrily as the small carton of cigarettes burst into flames.

"Oi! What are you playing at?" he yelled, jumping to his feet. He glared accusingly at Minerva, "That was my last bloody packet. I'll need to go to Hogsmeade to buy more, now."

"You have classes this afternoon!" she reminded him angrily.

"The students are welcome to join me if they like. Nothing wrong with going on a little field trip with their Professor. I'm joking!" he cried, laughing at the scandalised expression on Minerva's face. "Okay, okay, I'll stop teasing you. I'm sorry."

Minerva gave an exasperated sigh and sank into the seat next to her, "I've only been in your company a few minutes, John, and already I'm exhausted."

John drew her a cheeky grin, "You've missed me, haven't you?"

"Have I missed being on the alert for your high jinks every minute of the day? Certainly not," she replied sarcastically. They glared at each other in silence for a few moments before John broke out into a wide grin and started to laugh. Even Minerva couldn't help the smile teasing the corner of her thin lips. John had always been exasperating, but he was indisputably charming. Annoyingly so, in her opinion. Their banter had always played out much the same way during his school days - he would get into trouble, Minerva would chastise him and give him detention, but he would always end up making her laugh. He was impossible to stay angry at for long; his charm was what Minerva contrarily liked and disliked about him the most. She gave him a searching look, "Why are you here, John? Be honest with me."

"I'll be honest with you if you're honest with me," he offered. "How about we take turns about asking and answering each other's questions. Sound reasonable?"

Minerva took a moment to consider the offer before giving him a curt nod in agreement.

"Very well," she sighed. "But no more of your cheek, John. I want straight answers out of you from now on."

"Deal," he nodded. "Okay, here's my first question - how are you, Minnie?"

"Stressed," she replied honestly. "Where have you been these last few years?"

"To Hell and back - literally," he replied before asking. "Dumbledore asked you to keep an eye on me, didn't he?"

"Of course he did," she replied coolly. "Can you blame him?"

John shook his head. He didn't look offended at the admission, "Given my track record, I expected as much. He must have been pretty desperate for someone to take the job if he gave it to me so easily."

"So, why are you really here?" she implored. "Why did you ask for a job you obviously don't want?"

"I'm here for the books. Really," he replied sincerely as Minerva tsked at him. "There are books here that I can't find anywhere else in the world. And before you ask, I'm not a hundred percent certain which books I'm looking for. I just know that if I'm to find what I need, it'll be here. It has to be; I've searched everywhere else."

"For what purpose?" she asked again. John hesitated. Minerva raised her eyebrows in surprise - for the first time in the many years she had known John, he looked embarrassed. Ashamed, even.

"John..." she asked slowly. "What kind of trouble have you gotten yourself into?"

John gave a nervous laugh, "Nothing I can't handle myself, love- Professor." He quickly corrected himself as Minerva drew him a dangerous look. He sighed and rubbed his tired eyes, "Let's just say that I got myself in a bit of bother when I was in Newcastle. I don't want to get into the details but I hope to find a book that will help me umm...fix something I messed up."

"I thought we were going to be honest with one another," she reminded him. John's evasiveness piqued her curiosity. What on earth was he up to this time?

"I did say that, didn't I?" he grimaced. He sighed in resignation, "Fine, if you really want to know why I came back to Hogwarts, I'll tell you. But you're not going to like it." A mischievous grin slowly spread across John's face, "In fact...I'll do one better than that - I'll show you. Do you have any free periods tomorrow?"

"Yes, I'm available after three o'clock tomorrow," she confirmed, curious to what he was proposing. John grinned and clapped his hands together.

"Brilliant! Come to my classroom tomorrow, I'll have a little demonstration ready for you and my students. After that, I'll explain everything."

"Is this demonstration dangerous?" she asked sceptically.

"I wouldn't be teaching my class properly if there wasn't an element of danger involved," he smirked. He rolled his eyes at Minerva's worried expression, "It'll be perfectly safe! Trust me, I know what I'm doing."

Minerva frowned, "Is it really necessary to put on a display? Wouldn't it be more convenient just to tell me now?"

"Nah, it's easier just to show you what I'm after," he argued. "And it'll make for a pretty spectacular first lesson of the year. Killing two birds with one stone."

Minerva sighed, "Very well. I shall attend this little demonstration of yours, but only on the condition that you promise to attend all of your classes from now on."

John groaned, "Christ almighty, you're busting my bollocks already and I only just got here!"

"I hope you won't use such colourful language in front of students," she warned.

"Most of my lessons will need to be conducted in silence, then," he joked. He sighed resignedly and shrugged, "Fine. I'll attend all of my lessons from now on. And I'll mind my language."

"And no smoking during lessons, either," she added, pointing an accusatory finger at the overflowing ashtray. John clicked his fingers and the pile of cigarette butts and ash vanished.

"And no more bringing girls back to the school," she continued, then quickly added, "Or boys. This is a place of learning, not a frat house."

John laughed, "You're determined to take all of the fun out of teaching aren't you? What will you do if I break any of your rules - give me detention again?"

"Don't think I won't," she warned.

"Is that a promise?" he asked silkily. She fixed her expression into one of steely disapproval.

"You keep your bad habits to yourself, John - and preferably away from the students," she warned. "I'm willing to start things on a clean slate with you, but mark my words; if you bring harm to my students, I will remove your testes - without magic - and use your pitiful marbles in a game of Gobstones. Understood?"

John's smile faltered and he swallowed hard, "Understood, Professor."

"Excellent," she said briskly, rising to her feet. "Now, as much as I enjoy sitting here chatting to you and ensuring that you stay out of trouble, I have classes to prepare for - as do you. I'll see you at dinner."

"It's a date!" John called after her.

"It most certainly isn't!" she cried over her shoulder, slamming the office door shut behind her.