AN: OK... I'm rubbish at summaries, so if you're reading this you obviously weren't put off!

A few things before we get started... I have taken quite a lot of liberties with the worlds of OUAT and HP in this fic. The biggest change is probably that Henry is Regina and Daniel's son, because it worked way better that way - actually, it only worked that way. Also, Mary Margaret and David aren't Emma's parents.

A lot of pairings are gonna be touched on/hinted at in this fic, most notably Stable Queen, Swan Thief and the biggie, as always where I'm concerned, Swan Queen. Oh, and Hook and pretty much any female in a 50 mile radius ;)

I'm gonna explain in advance, because it may confuse people otherwise, that Cora is the mother of Bellatrix, Andromeda and Narcissa through marriage to Cygnus Black. Then he died and she married Henry and they had Regina. Therefore Regina is the half-sister of Bella, Dromeda and Cissy and the aunt of Tonks and Draco :)

I think that's everything... oh, this is set from the beginning of Half-Blood Prince and will focus more on the books than the films because, as much as I love them (and looking at Rupert Grint's face) the amount they missed out just irritates me...

Parts written in italics are flashbacks.

OH. I guess this fic is dedicated to Lauren and Lucy, who made the appropriate complimentary noises when they were allowed to read sneak peeks and who I am spending my time attempting to enlighten about the fact that Swan Queen is endgame :)

Disclaimer: I don't own Once Upon A Time or Harry Potter... or they'd probably be quite different.

I'm gonna shut up now and let you read... feel free to let me know what you think!

Regina Mills strode through the deserted corridors of Hogwarts School in search of her son. She had a good idea where he would be and was less than impressed that she needed to remind Henry and her best, or rather only, friend that the students would be arriving at the Castle for their new year of learning at any time now.

Since accepting Dumbledore's offer of a job less than a month previously, Regina had been questioning and second-guessing her decision constantly. One moment she was convinced she'd done the right thing in accepting the position and, minutes later, she was adamant that the opposite was true. Severus had done his best to assure her that she had made the right choice, but even his usually calming words had done nothing to soothe her anxieties.

Her worries had increased further when, a week before the students were due to arrive, Regina and Henry had moved into the Castle. Memories hit her hard; happy and sad and everything in between. The witch almost longed to be the eighteen-year-old she had been when she walked these corridors last once more. But too much time had passed, too much had happened and Regina barely remembered who she had been back then.

"Hey, Mom!" Henry grinned at her as she entered one of the Defence Against the Dark Arts classrooms.

He was sitting cross-legged on the desk, while Severus lounged in his chair, facing the boy. As Regina waited for some form of explanation, her arms folded over her chest, he smiled lazily and shrugged.

"What have you two been getting up to?" The woman asked after a moment or two when it became clear that no one was going to volunteer the information.

"Uncle Sev was teaching me to block people out of my mind."

"Occlumency? Really, Severus? He's thirteen."

Severus shrugged. "He's a smart boy. I thought he could handle it. As it is, he is proving a far more skilled Occlumens than the Potter boy. Besides, with Cora around..."

"Yes, well..." Regina attempted to hide her unintentional, yet very visible, flinch at the mention of her mother. "Henry, dear, run up and get ready for the feast. Everyone will be arriving soon."

The boy nodded and slid off the desk, grinning at the adults as he rushed from the room. Regina hoped he didn't bump into Filch during what she assumed would be his sprint through the Castle towards his common room. She had already had several arguments with the caretaker over her son and they had only been there a week.

"Have you stopped questioning whether you were right to take the job?" Severus asked, seeing her struggling with her thoughts.

"Not really."

He smiled. "Dumbledore approached you personally; that should tell you just how much he wanted you to take the position." As Regina sighed, he shrugged. "Now, if you don't mind, Professor Mills, I need to change into my robes before the feast. I'll meet you in the Great Hall." He began to ascend the spiral staircase in the corner of the classroom which led to the office and, from there, to Severus' private quarters. "Oh, Gina... try not to worry."

With a brisk nod, the witch turned and stalked from the classroom, heading in the vague direction of the corridor that housed the teachers' private chambers. Her mind, however, had returned to the late July evening when Professor Dumbledore had made her an offer she found she was unable to refuse.

Regina sighed at the soft, yet firm, knocking on her front door. She glanced towards the kitchen table where her son was sitting with his nose buried in a book. The sight was nothing new and the brunette witch was well aware that there was no use trying to get Henry to answer the door. Instead she sighed again and dried her hands on a dish cloth before moving through the house to the entrance hall. Fluffing up her already perfect hair and straightening her clothes, Regina pulled open the door, fixing the figure on her doorstep with a stern glare.

"Oh…" Her expression faltered as her eyes fell on the tall, bearded man who was sending her a warm, knowing smile. "Professor… how can I help you?"

Dumbledore motioned towards the doorway. "Would you mind if I came in? It looks like rain and I'm wearing my good cloak."

"Of course." Regina moved backwards to allow him entrance. Once he had swept inside, looking around interestedly at her tastefully decorated hallway, she closed the door; though not before shooting a quick, almost fearful, look around her darkening driveway. "So, Professor Dumbledore, to what do we owe this pleasure?"

Ushering him into the study, the brunette smiled and perched awkwardly on the edge of the large, upholstered armchair beside the fireplace, watching as her son's headmaster settled himself on the sofa and looked around. For a couple of moments Dumbledore remained silent, appraising her furnishings with a bright smile. As Regina's discomfort grew and her fidgeting became more noticeable, she stood and crossed to the drinks cabinet in the corner of the room.

"Can I offer you a drink?" She asked, resisting the urge to down the glass of Firewhisky she had poured for herself in one go.

"I won't say no to a glass of Spiced Mead if you have one."

With a nod, Regina rummaged in the cupboard and pulled out a bottle. She wrinkled her nose at it sceptically, remembering receiving it as a gift from her older sister, Narcissa, the previous Christmas. Assuming it was safe to drink as she got on well with Cissy, she poured the wizard a generous helping and handed it to him with a small smile.

"Now, Regina, I'm sure you're eager to know the reason for my visit."

"Well, yes…"

"I have a proposition to put to you." He informed her, taking a sip of his drink and sighing appreciatively. Regina held back an exasperated growl as he took a further sip, before complementing her on the beverage, as though she had manufactured it herself. "This year I am hoping to persuade a new Potions Master to join our ranks or, rather, persuade an old one to re-join our ranks. I'm sure you remember Professor Slughorn. Severus will be taking over the position of Defence Against the Dark Arts Master." He spotted Regina's arched eyebrow and chuckled. "I am well aware that the appointment will raise many questions, but you and I both know the man Severus truly is."

Regina nodded slowly, not commenting on the words the Professor had just uttered. "And what, precisely, does this have to do with me?"

"I would like to ask you to join the Hogwarts staff as a second Defence Against the Dark Arts Professor."

"What?"

Dumbledore chuckled as Regina simply gaped at him, his offer hanging in the air between them. "I think it is safe to say that Severus will have more distractions on his time than usual this year and we have discussed the idea of hiring you to teach classes alongside him. He agreed it was a wonderful idea."

"Professor Dumbledore, I–"

"Albus, please."

Regina almost blushed. "A-Albus, I… thank you, but I have no experience of teaching… I'm not sure I could. Besides, my mother…"

"How is Cora?" Dumbledore asked with a warm smile. "I was her Transfiguration Professor, you know. She was unusually skilled, particularly at Human Transfiguration as I recall…"

"Yes," Regina agreed bitterly, "she is."

"So? Shall I tell Severus you've accepted the offer?"

The witch faltered for a moment, considering the pros and cons of becoming a member of the Hogwarts staff. She was definitely lonely when her thirteen-year-old son was at school and the thought of spending the whole year in such close proximity to him once more was certainly tempting. On the other hand, she knew that her mother would be far from impressed. At thirty-six-years-old Regina hated that many of her decisions still rested on what Cora would think.

"Hey, Mom, did you know that–" Henry burst into the study but stopped abruptly at the sight of his headmaster sitting on the sofa nursing a glass of mead. "Oh, hi, Professor Dumbledore."

"Good evening, Henry." The man nodded towards him, smiling warmly. "Enjoying your summer?"

"Yeah, it's OK." The teenager agreed. "But I'm looking forward to going back to school."

Dumbledore chuckled. "I'm glad to hear that."

"What are you doing here?"

"Henry!" Regina scolded with a frown. "Manners."

Dumbledore waved her scolding away with a smile. "I was offering your mother a job, dear boy. I would very much like her to take a joint position of Defence Against the Dark Arts Professor alongside Professor Snape."

"Uncle Sev isn't the Potions teacher anymore?" Henry asked with a light frown. "Why not?"

"We've got a new Potions master, Professor Slughorn. He taught your mother when she was at Hogwarts."

"Really?"

"Yes, dear." Regina agreed distractedly.

She was irritated that Dumbledore had mentioned the job to her son before she'd made a decision. The brunette knew that he was hoping that Henry would be able to convince her to take the job. Regina knew that, if Henry asked it of her, she would do it without question. There was nothing she wouldn't do for her son.

"So are you gonna take the job, Mom?" Henry asked, looking at her carefully.

"I'm not sure yet, sweetheart. There are things to consider." She snuck a glance at him, trying to gage his feelings on the matter. "What do you think about the idea?"

The boy broke into a huge smile. "It would be awesome!"

Regina's expression softened instantly and she held out a hand for her son. Henry hugged her tightly, grinning up at her as she cupped his cheek with her hand and smiled down indulgently.

"Well then, I think that's sorted." Dumbledore announced, taking the moment as Regina's acceptance of the job offer. "We'll expect you at the Castle a week before term starts. Henry is, of course, welcome to come with you then."

In front of the large mirror in her bedroom, Regina scrutinised her appearance carefully. She had always been taught that it was unacceptable not to look her best at all times and that was something she kept to. Patting her immaculate hair nervously and pulling on the hem of the black jacket she wore underneath her teachers' robes, the brunette took several deep breaths, preparing herself for the evening ahead.

In the week she and Henry had lived at Hogwarts Castle the majority of her time had been spent in limited company; her son and Severus mainly, but there had been the necessity for the odd meeting with the Headmaster and Deputy Headmistress, Minerva McGonagall. Regina respected both Professors immensely and was grateful that neither seemed to view her as simply a part of her family or her mother's daughter. To them she was simply Professor Regina Mills, Defence Against the Arts teacher and Henry's mother.

With a final glance in the mirror she fixed her slightly haughty mask in place and turned to stride from the room. The corridors were deserted, much to her relief, until she reached the Entrance Hall and found Minerva waiting to greet the new first years. The older woman smiled tightly at her and informed her that some of the other staff were already taking their places and she'd heard word that the second years and above were about to descend on the Castle.

Chuckling softly, Regina nodded at her and took yet another steadying breath before opening the heavy wooden doors and striding towards the long dining table on the raised platform at the far end of the Great Hall. The clicking of her heels in the relative quiet caused the members of staff already seated to turn and look at her. She knew them all of course, some from the time she'd spent at Hogwarts as a student and others from the brief meeting Dumbledore had called during her second day in the Castle.

A group of five young women caught the majority of her attention and her lip curled involuntarily into a sneer. One of the women had very short black hair, one had long brown hair and a red streak clearly visible in it, the third had wavy brown hair and big blue eyes, the fourth long auburn hair and the fifth, the most irritating in Regina's opinion, had long, blonde Princess curls. She pointedly ignored the curious gazes aimed in her direction and took a seat at the other end of the long table beside Horace Slughorn, leaving a free seat on her other side for Severus when he finally appeared. Immediately she was drawn into conversation with her former Potions Master who seemed eager to remind her of her days as part of his elite group of students.