Only three students had elected to remain at the castle over the holiday, all of them Hufflepuffs. On Christmas Eve, the students were treated to a special dinner in their common room, and the staff had a gathering in the staff room. They ate and drank and made merry, and Severus got a headache.

These little gatherings had a way of reminding him that he had friends in his colleagues. They were too busy to spend time together regularly, and they were often at odds over something or another, but they were his friends nonetheless. Filius Flitwick was always good for a game of chess. Pomona Sprout was probably his closest friend at the school other than Minerva, considering they coordinated regularly where plants as potions ingredients were concerned (and she'd been the one professor when he was a boy who hadn't seemed to mind that he was an ugly little outcast, and had gone out of her way to pat him on the shoulder whenever she saw him; it was a small thing, but it had meant the world). Sinistra didn't like him, but she was polite, and she was downright hilarious when she was drunk. Hooch was forever making a pass at him, which had been awkward in the beginning but was now a running joke; she even trusted him to referee Quidditch matches when she was indisposed. Pince hated him in a sulky kind of way because he had a habit of writing in books. He got on well with Vector, though he'd developed a strange jealousy in the past months when he'd realized that the young Hermione spent large chunks of time in the Arithmancy professor's office playing the protégé. And then there was Hagrid, of course; the gentle half-giant always seemed too cheerful, and he trusted him on faith in Dumbledore, which had begun to hurt.

After Filius had thoroughly trounced him for the second time that night, Severus's queen solidly refused another match under his direction. Minerva howled with laughter, switching him out. Severus watched for a bit, distractedly discussing an article Arithmancer's Quarterly that Hermione had told him about with Vector.

"And what else did she say about that little article?" Hooch asked from the other side of Vector, bringing Severus up short. She?

"I beg your pardon?"

"You just said you hadn't read the article yourself, but she told you—something about quadratics," Hooch said, waving a hand as if to dissipate the unfamiliar term. Severus's smirk came out more of a sneer.

"I do talk to people, you know," he said evasively. Make something up, his brain screamed, but his mouth couldn't seem to catch up. He felt blind-sided, but he couldn't think why. It wasn't like the relationship was inappropriate, not really. Dumbledore wouldn't like it much, but not in a professional capacity. No, he sneered to himself. Not in a professional capacity, but in the way that it isn't fitting to have your spy and your assassin sharing confidences, let alone sleeping together.

"Yes," Vector said, her tone almost teasing.

"Just not usually of the 'she' variety," Hooch said, grinning. Almost leering. Severus rolled his eyes.

"You are a 'she' and I talk to you regularly," Severus said. "As are you, Septima. And Minerva."

Vector's eyes danced with amusement. Hooch continued to grin, turning her head and shoulders around as she searched the room.

"Where's Poppy?" Hooch asked when her quarry wasn't immediately spotted. "She's the one who knows everything. Poppy! Who's Snape sleeping with these days? He's bloody cheating on me, the bastard."

Severus pinched the bridge of his nose. It was nights like this one that would make what was coming so difficult.

Vector returned to their academic discussion once Hooch was gone. She was quickly going on about a theorem that was well past his skill. He could work out substitutions and amendments to potions formulas just fine, but it had been years, decades, since he'd really worked through the theoretical stuff.

Poppy found him a bit later, smirking at him, and asking what Hooch was on about.

"I'm sure I don't know," he said testily. "She was a bit in her cups."

Poppy laughed gaily. They were joined after a few minutes by Pomona and got to talking about mandrakes, of all things. It was a very pleasant way to spend an hour.

He was the first to leave the gathering; he almost always was. Slughorn had started trying to talk to him, and Severus didn't want anything to do with his old Head of House. The man hadn't cared a lick for him when he was a student, when he was supposed to be the one looking out for him and standing up for him. Now that he was interesting—the youngest Potions Master in an age, and holding a position of "influence" near Dumbledore to boot—the idiot wanted to pretend like they'd been the best of friends once upon a time. It left a sour taste in Severus's mouth.

That sour taste vanished immediately when he made his private sitting room and found Hermione curled up on the sofa, Ars Alchemica open on her lap. She wore a deep maroon robe with subtle black embroidery, covered from wrist to clavicle. The robe had tiny black buttons down the front, stopping mid-thigh like all the robes she favored, leaving the skirts of the robe to gap open around her legs and show the long gray skirt she had on beneath. Her boots were tucked neatly under the side table next to the couch.

He brushed her mind with his in greeting, closing his eyes and breathing deeply when she brushed his in return. He'd missed it. He'd missed it so much. All the letters in the world couldn't make up for that single moment of mental contact.

"Hello," he said when the ache of relief had subsided. He opened his eyes and looked at her. She hadn't moved, but she was looking at him now instead of the text.

"Hello," she returned. She wasn't smiling, but he could feel the grin in her very presence. She was happy here, in this room, with him. The ache came back, but it was different.

I've missed you. He couldn't quite say it out loud, but that wasn't the only way he could communicate with her. She smiled.

"I've missed you, too."

She stood and crossed to him, wrapping her arms around his waist and laying her head against his chest. She was so small. It surprised him every time. She had a presence, a sheer force to her that made her seem bigger. The sixth year in his classes had reached her full height already, and the woman in his arms came up to his chin. It was the perfect height for resting her head against him so that he could put his chin on the top of her head and hold her. They fit together like they'd been made for it.

"How long can you stay?" Does Dumbledore know you're here?

"How about forever?"

"That would be agreeable."

She smirked against his neck; he could feel her teeth. He moved away and put a finger under her chin to tip her lips up to his. The kiss was long and slow, as if they had all the time in the world. But they didn't.

"And no, to answer that last bit," she said when they finally broke apart to breathe. "Dumbledore doesn't know I'm here."

He smirked, pulling her closer and kissing her temple. "That means he won't come looking for you."

"Precisely."

They stayed in the doorway for a bit longer, holding each other. It was really quite silly, as she'd said before when they'd sat in the reading chair for such a long time just holding on. He'd never known a relationship, sexual or otherwise, that had involved quite this much drive to simply touch. It was almost a separate thing from the need to bury himself in her, to rise over her and slide home and make her keen. He needed to hold her, too. To wrap her up and never let her go, and always know that she wasn't sad or hurt. To cherish her.

"It's Christmas, Severus," she said after a long time. "Take me to bed?"

Slowly, he moved his hands down from where they'd been wrapped around her ribs holding her close, mapping the familiar lines of her waist, cupping around her ass, gripping, lifting. She pulled her skirt up out of the way with one hand so that she could wrap her legs around his waist, and the other hand held tight to his shoulder. He couldn't decide if he enjoyed the feel of her ass in his hands or her quim pressed to his cock through the layers of their clothes better.

Hermione leaned down and kissed him as he carried her to the bedroom. A deep, open-mouthed kiss full of promise.

Gods, but he loved this woman.

\\

Severus had never had pleasant Christmas mornings when he was a child. Even before the mill closed, his parents hadn't had much money. He usually got a new pair of shoes and, if he was lucky, a comic book. There had been a few very strange Christmases spent at Malfoy Manor when he was being recruited to the Death Eaters, showered with gifts. Those memories had gone bitter with time.

At Hogwarts, Christmases were always pleasant but tinged with loneliness. Most professors had come to the school after living their lives. Their children visited at Christmas, or they went visiting, seeing friends if they didn't have family. Severus had no friends outside the walls of Hogwarts, not really, and he had no family at all. His Christmas morning was spent alone, opening the perfunctory gifts—some better than perfunctory, of course, but mostly they were just a courtesy—in his sitting room alone, wiling away the time until Christmas dinner in the Great Hall, then back to life as usual.

Waking with Hermione tucked against his chest, every inch of her molded to every inch of him, was a pleasant change of pace. He looked down at her, his arm tightening around her of its own accord. She smiled in her sleep, nestling her head more comfortably against him.

He let himself drift between waking and sleeping, waiting for her. It was still quite early. Sometime around six, Hermione stretched, the movement sliding her flesh against his in the most delightful way. She rolled so that she was laying half on him, crossing her arms over his chest and putting her chin on her arms. Her breasts were pressed to his chest; he could feel her nipples hardening against him just as surely as she would feel his cock hardening against her thigh.

"Good morning," she said, smiling at him like the cat that got the canary. He smiled back.

"Good morning."

She shifted ever so slightly, moving so that her legs were on either side of his, and he was pressed into her. He gasped, his arm tightening around her again, his other hand finding the place where they were almost connected and making adjustments, opening her folds so that he could slide in properly. His thumb found her clitoris and he rubbed a gentle circle. She was still lazily sprawled on his chest, her arms crossed; her eyes dropped closed and she practically purred.

He removed his hand, bringing his wet thumb to his lips and sucking it clean. She watched him with dark eyes, her hips beginning to twitch against his. He didn't think he could stand the teasing anymore, even if he'd been the one to start it.

Severus held her head, bringing her lips to his, and used the grip he still had around her waist to keep her close as he rolled them. She moaned against his mouth as they shifted together, as he shifted inside of her. He couldn't seem to get enough air, but that didn't stop him from kissing her.

She bent her knees, anchoring her feet on the mattress as he began to thrust. He braced himself with arms on either side of her head, driving into her. The bed creaked beneath them, the headboard thumping against the wall in time with their movements.

Hermione was shouting affirmations—"Yes, yes, yes!"—with each thrust, her hips rising to meet his, her fingernails digging into the skin on his back over his ribs. He was grunting in an embarrassingly animalistic way, but she didn't seem to mind so neither did he.

"Oh," he said at last, more of a groan than a word, and he released. Suddenly boneless, he collapsed on top of her, shoving himself further up and into her. She clenched around him, her body milking his as she screamed her climax.

"Jesus Christ, Severus," she whispered, running her fingers through his hair. He bit her neck gently, then kissed the same spot. He turned his head, licking and kissing his way up the other side of her neck, across her jaw, finally finding her mouth.

It was quite awhile before they finally made their way to his sitting room. He had his dressing gown, and she'd picked up his shirt from yesterday off the floor by the bed. It was too big for her, but she'd rolled the sleeves up and didn't seem bothered by the way it hung loose around her. Or the way it didn't cover a thing when she bent over to stoke the fire up in the cool room.

He had to look away. He wanted to stand behind her, to pull her ass against him and rut like dogs. He had to look away not because he was ashamed, but because she would approve of the action and then they'd never get anything done with the day.

When she turned around she was smirking, and he knew that she'd caught what he was thinking. Or possibly she'd had the same idea all on her own.

"Happy Christmas, Severus," she said, going up on her toes to peck him on the lips. She pressed her hands to his chest for balance, and he took them in his own, twining their fingers, leaning into her kiss, deepening it while carefully keeping himself from pressing their bodies together.

"Happy Christmas, Hermione," he said when they broke apart. Her lips were swollen from the kiss, her eyes dark.

He didn't have a Christmas tree in his quarters; he never had. His gifts were arranged in a little stack on his desk, with three packages off on the corner. His chest constricted a bit at that—Hermione Granger, Gryffindor golden girl, had even fewer presents at Christmas than the bat of the dungeons. How had it been all those years, Turning back to before her friends knew her, spending the holidays alone?

Hermione didn't seem fazed by it. She picked up the package from Dumbledore, and neither of them were surprised when it was a book. A big, thick thing with an ancient cracked-leather cover. She settled on the couch and began flipping through it as he unwrapped his gifts at his desk.

Sprout sent the usual basket of prized ingredients from her greenhouses. Minerva's gift was a tasteful jumper, incredibly soft and charmed to be warm without being overly hot, but in an unfortunately garish crimson. Dumbledore had gotten him an enormous mix basket from Honeydukes, and a small blank journal with a cerulean cover. Hooch had given him a year's subscription to the Holyhead Harpies newsletter and the team's calendar (the sort to be hung on the wall, with a picture of the team for each month and all the games and open practices marked). Filius's gift was a set of glass vials, charmed unbreakable, and a soft felt bandolier to carry them in. Slughorn had gifted him a bottle of rum with a bow on the neck. Vector had gotten him a subscription to The Potioneer and written him a nice card. The Malfoys had sent a prized bottle of elf-made wine.

Underneath all the usual gifts was a flat dossier with the official look of the Ministry to it. He cast a few detection spells before he opened it and pulled out the sheets of parchment within. Three identical squares, a document in triplicate.

He looked up at Hermione, noting that she had just opened his gift to her. He'd expected it would take him months to find the right ring, but he'd found it almost before he'd realized he planned to ask her at Christmas. He hadn't expected her to be with him for Christmas, so he'd written it all out and folded his proposal up in the little velvet box. The note was in her hand now, and the ring was on her finger. A gold band with three identical diamonds set into it (because she hated jewelry primarily because it was always getting caught on things, so she wouldn't want a ring with a gem in a setting that stuck out). A diamond for each part of him that she possessed—heart, mind, soul—as he'd explained in the note.

His heart thumped a little too hard and his stomach fluttered with nerves, but the symptoms vanished when she looked up and smiled at him.

"We seem to have had the same idea," Hermione said, leaving her gifts—she'd gotten a tin of biscuits from Minerva to go with her book from Dumbledore—on the couch and coming to lean against his desk, her hand finding his. The ring hadn't warmed against her skin yet, so it was a cool spot between his fingers when their fingers laced together.

"I will likely die before the war is over," he said, even though he'd written as much in the note. "I don't like making promises I can't keep, but if we marry I can… you'll have my assets when it's over. If they're not seized or destroyed out of hand, of course."

"Severus," she said, almost sharply. She took the folder from him and held up the parchment. It was a marriage license, their names and information in all the correct blanks. All it needed were their signatures and the signature of a witness. "When the war is over, you and I will go together and file these in the Records Office. And we will glare at anybody who protests. And we will have children—plural. And we will… Oh, I don't know. I don't know what we'll do, or where we'll be, but we'll do it together, and we'll be there together."

"Hermione—"

"I know you want to live."

"Well of course I do!"

"So start acting like it," she said, practically a growl. "Make plans for the future with me."

"I don't like to make promises I can't keep." He sounded petulant, but he didn't care.

"We're at war, Severus. I'm almost as likely to wind up dead as you are." His stomach plummeted. He knew it was true, he just had been very careful not to think about it since the last time they'd had this conversation. She held up a hand, apparently seeing protest on his face. "I refuse to let the Dark Lord and all this determine how I live my life. No, I know. It affects almost every aspect of my life. I just don't want to give another inch. I don't want to give it my future. I don't want to come out the other side—and I have to believe that I will, that we will—and find myself at odds about what to do. At least not with you. I want to know that nobody will be able to question us about this. That we can show them our license and tell them to stuff it, this isn't some crazy cathartic whirlwind."

He knew exactly what she meant. He could even almost agree with her. But he couldn't quite bring himself to hope that he would survive. He'd been trudging toward this death for too long to believe it could be any other way, even if he wanted to.

But they were in agreement, at least, that they would be married.

Severus took the papers from her, looking at them properly. It was the standard marriage license, combining assets and accepting any debts of the other as their own. She'd own half the dung heap that was Spinner's End, have a key to his vault at Gringott's, and the wards at Hogwarts would react to her as the spouse of a teacher. In the event of his death, she would take full ownership of his books and the potions equipment in his Hogwarts lab he'd bought with personal funds, and she'd hold his patents. Similarly, he'd have a key to her vault at Gringott's and access to her Muggle bank accounts as well. She didn't own any property, but he'd receive royalties from her published articles (none under her own name, of course) if she were to die.

Also, according to the last line of the document, where the parchment waited for her second signature, she'd be taking his name.

"Severus! Love. Don't cry!"

She took the papers from him, setting them on the desk and sliding easily into his lap. She wrapped her arms around him, and his arms came up to hold her reflexively. He didn't know why that set him off, her taking his name. Did that make it more real, was that it? No. It was that he hadn't actually thought it would ever happen.

Hermione Snape.

Good gods.

She wiped the tears off his face, smiling up at him. Her eyes were a bit watery, too. He smiled, and she kissed him.

"I'm afraid all you get out of marrying me is a mess of false documents that will need to be sorted out after the war," she said after awhile. She got off his lap and Summoned her satchel, pulling another ream of papers out of it to show him. She settled on his lap again, this time with her back against his chest so that she could show him the documents over her shoulder as she talked. "These are for you, though. So you'll know what to look for."

"What are they?"

"My aliases." She chuckled. "Dumbledore set me up with different identities in all that Time Turning, and here are the names and addresses for all of them. All the mail is rerouted to the flat in Edinburgh at the moment. The only active name is Sam Barnes, but the addresses are still warded if you ever need a place to go to ground. All the wards will let you in; I altered them last week.

"And this is more exciting," she said, shuffling her papers around to a section that was Muggle printer paper with a bank's logo at the top. "Banking. Since I've been mucking about with time, all my banking has been done in the Muggle world. The goblins would be too hard to trick with fake identities, and they'd probably get mad about it if we tried, so everything is in Muggle banks except for the fund my parents set up when I started at Hogwarts. Dumbledore has more or less funded me entirely, so the bits I've earned on the side have just been accruing interest. Not as much as they would've if they'd been going through time the way I have, but still."

She handed him three plastic credit cards, each with the name Simon Blake on them, and each for a different bank.

"Who is Simon Blake?"

"You are," she said, shuffling her papers around again. She handed him Muggle ID and a passport, both with his face on them and more-or-less his information. "I can't put you on my lease, of course; that would definitely tip Dumbledore off. I tied everything else together that I could, though."

He kissed her cheek through her hair, taking the documents from her and stacking them together again, setting them on the desk.

"Do I look like a Simon?"

"Not really," she said, turning a bit in his lap so that she could kiss him properly.

\\

He sat through a torturous Christmas Dinner with his colleagues. Their company had been quite nice the previous evening, but that was before he knew he could've been spending time with Hermione.

His fiancée.

Hermione herself had unpacked a bit, clearly planning to spend the rest of the holiday in his rooms, and settled in with her new book. He'd dressed and had a look over his gifts again, making sure he'd remember what to thank each of them for, but he'd been dawdling.

"You aren't usually so eager to be away," Minerva observed from her seat next to him. He willed himself to slow down. It wouldn't do if he gave himself a stomachache from eating too fast. "Do you have other plans?"

It was said lightly, but the way she'd turned so that Filius on her other side wouldn't hear indicated she thought he might be headed for the Death Eaters.

"No," he said shortly, taking a long sip of wine. "Just… hungry."

"Hm."

"Minerva?" he asked quietly after awhile. They were well into desserts now, but he couldn't bring himself to more than pick at the chocolate pie on his plate.

"Are you alright, Severus?"

"Yes. I promise you I am," he said, smiling slightly. Down the table, Dumbledore laughed cheerily at something one of the students had said, then rose and wished those he'd been talking to a Happy Christmas before he made his way out of the Hall.

"Are you sure? You seem… off."

He almost smiled. But that would be a sure way to attract the headmaster's attention. "I was wondering if you'd join me in my sitting room for tea this evening."

"Gladly, Severus. Gladly." She said it with such a genuine smile that he really did smile back at her. One of the Hufflepuffs choked on his pumpkin juice, and Slughorn pounded him on the back jovially. Severus glowered at the pair of them.

When he returned to his rooms, she wasn't there. He came to a full stop, his heart hammering in his chest. It was like he'd had a very pleasant dream only to have it twist itself into a nightmare.

She'd left him a note. The world started turning again, if slowly. She was meeting with Dumbledore. She'd be back.

He spent half an hour pacing his quarters, rearranging his things, pulling papers out and making little stacks on his desk, before he finally sat down and stared at their marriage license. Hermione Snape. Holy shit.

He felt her coming long before she arrived. Not in the good way where he could sense her mind, but in that she was fairly vibrating with tension. A few of the candles went out when she entered the room, and the single throw pillow he had on the chair by the fire (not his reading chair, but the one he never used) puffed up a little bit as if it wasn't sure if it was going to explode or not.

"I have good news and bad news," she said, coming to lean against the desk next to him. She was wearing a Muggle dress, down to just above her knees and sleeves to her elbows, lace the color of buttery cream with a thin brown belt around her waist. She looked deliciously feminine. He wanted to touch her, and he didn't restrain himself; for once he didn't have to. He put his hand on the nearest knee, running it up her thigh to just beneath the hem and back down. It seemed to calm her. He raised an eyebrow at her, and she continued speaking, "The good news is that I'll be staying at Hogwarts. The bad news is that I'll be picking up my timeline where I left off."

"You'll be a student."

"Yes."

He couldn't help it: He laughed. He laughed long and hard.

"That will be more tolerable than the other you running around these halls," he said, resting his hand just above the back of her knee. "You'll know what it is when I do this." He brushed her mind with his, and she smiled back at him.

"I'll be in Gryffindor Tower. I'm supposed to stick to Harry like glue, let him get into his trouble but keep him out of harm."

"So basically what you'd been doing anyway."

"Yes. But…"

"Yes," he agreed. "But."

\\

Minerva arrived an hour or so later, bringing a bottle of red wine with her.

"Hermione! My dear, I had no idea you were in the castle" Minerva said upon entering the room, then gave Severus a shrewd look. "Though that does explain why Severus was in such a hurry to finish Christmas dinner."

"Hello, Minerva," Hermione said, hugging the older witch. It struck Severus that he should be more nervous than he was. Minerva was just as much Hermione's surrogate mother as she was his; this was like bringing the girl home to meet the parents and going home to meet her parents all rolled into one.

Not to mention the part where they intended to modify Minerva's memory when it was all said and done. The thought of it didn't sit particularly well with him.

"Shall we have the wine, then?" Severus asked, transfiguring the teacups he'd pulled out into wine glasses.

They sat together, enjoying the wine and chatting. Hermione explained about Dumbledore's plan for her to pose as a student, and Minerva was duly amused. After almost an hour, Severus noted that he and Hermione had situated themselves rather comfortably close to each other on the couch, and Minerva was eyeing the space between them with a badly-concealed smirk.

"Out with it, Minerva," he said. Hermione hid her smile by taking a sip of wine. He nudged her with his shoulder.

"It's nothing, Severus," she said quickly, smiling outright now. "I'm just glad to see you two are friends. Really. You've both been isolated by the war, by the—by the tasks the headmaster has set for you."

"Yes, I suppose we have," Hermione echoed, twining her fingers with his, turning their hands so that they rested on his thigh with her hand turned up. Minerva finally noticed the ring.

"Actually, Minerva," he said, his nerves returning threefold. "I asked you to come down here for a reason. For the decent company as well, of course, but. Well. We need a witness."

"A witness?"

"Yes," Hermione said, Summoning the marriage license to them and holding it out to Minerva.

"Oh!" Minerva beamed. Severus's nerves vanished at that look. The Transfigurations Mistress was teary-eyed, her hand shaking as she traced a finger along the lines of text, not really reading it. "Oh, I'm so happy for you both. This is wonderful."

"Thank you, Minerva," Severus said, glancing down at Hermione. Her smile was so wide that he was almost nervous she'd break her face.

"You should have a party, you know," Minerva chastised a moment later, blinking the tears out of her eyes but continuing to smile. "You deserve to celebrate."

"When the war is done," Hermione said. She squeezed his hand. "We'll celebrate when the war is done and we can officially file that license."

"I suppose," Minerva said after a pause, giving him a sad look that meant she'd remembered he was a spy. Normally the look would've annoyed him, but something about it in that moment made him feel oddly cared for. Maybe it was Hermione's hand in his.

"Will you be our witness, Minerva?" Hermione asked.

"Of course I will."

They all stood, going to the desk because that's where the quill and ink were. There were two blanks on the left side of the parchment for him to sign, two blanks on the right side for Hermione (the second of them signed Hermione Snape), and one blank at the bottom for Minerva to attest that everything had been done above-board. The three of them signed each copy, then they went back in the Ministry folder, which went in the top right-hand desk drawer, and that was that.

"Well, the three of us will have a party," Minerva said. She went to the fireplace and ordered them dessert and more wine.

It was a very, very good night. Right up until they had to remove it from Minerva's mind.

Severus put a drop of sedative in her glass. Hermione removed the memory when Minerva was asleep, putting it in one of the vials he'd received from Filius for Christmas. They labeled it "Minerva, witness 12/25" and stored it away in the bandolier. Then he Obliviated the remnants of the memory from her mind (keeping it from reforming as memories thus removed did). Hermione left the room and Severus woke Minerva, sending her back to her rooms with a smile and a "thank you for a pleasant evening."

AN: If this seems a bit sudden, I apologize. I've moved this chapter around and rewritten it too many times to count. It just doesn't work as well if the marriage comes later (or not even later, still at Christmas but with a few other events thrown in beforehand). Whatever. Deal with it. Send me hang-ups and complaints and I will respond to them as best I can—or just enjoy the part where things are going to start happening now that she's caught up to herself in time.

One thing I thought of while editing but didn't have a good opening to address in-story was Dumbledore not being aware that Hermione was in the castle, despite his being headmaster and all the fancy wards keeping track of things like that for him. In my little world, the wards didn't ping him with her presence because she's supposed to be in the school—as a student, yes, but the magic can't tell that she's not the same as the girl in Gryffindor Tower, though if Dumbledore were to have had a more-than-glancing look at the whatsit that monitors the wards from his office it would have told him that there was a peculiar instance of a student being in two places at once; and after Christmas she'd register as a professor's wife (still somebody who was supposed to be in the castle, not worth a ping from the wards), which would have been more interesting if he'd noticed, but he didn't because there's a war on and even Albus Dumbledore can't keep track of every little thing. So Dumbledore remained unaware that Hermione was in the castle before and after the quick briefing he had with her directly after Christmas dinner.

Cheers!

— M