It wasn't a long walk to the office — my office, Hermione reminded herself firmly, my office — but with Snape ghosting along behind her in that soundless way he'd perfected over years of appearing directly behind misbehaving students at the worst possible moment, it was long enough to make her palms sweaty. She held her wand firmly, and put her other hand on the door. There was no handle. "Is there a password?"

"Weren't you listening to Minerva's explanation?" Snape sneered.

"To her —" Come and see me first thing when you reach Hogwarts, Minerva McGonagall's last message had said, when Hermione had owled back her signed contract. "I planned to go and see her once I'd had a look around."

He sighed. "Ah, Gryffindor caution and clearheadedness once again makes itself known."

Hermione turned and glared up at him. "Are you going to stand there being sarcastic, or are you going to tell me how to get in to the — to my office?"

"Put your hand on the door," he instructed. "Your wand hand. Can you feel the wards?"

She did as he directed, and concentrated. She knew what her own wards felt like, once she'd set them … she knew what the wards of other witches and wizards felt like, too, friendly and unfriendly both. There was nothing like that here, neither the slightly fizzing warmth of welcome or the cold sting of rebuff. But something … something running beneath her fingers, cool and pale and neutral like a net of silver wires, not just across this door but throughout the whole building. "I think so."

"Tell it who you are."

"I'm Hermione —"

"With. Your. Magic," he bit out.

"With my magic." Okay. With my magic. She closed her eyes and pushed a little bit against the silver net, wondering exactly how to do that but determined not to ask Snape to explain something he clearly thought was obvious. Perhaps a patronus? Although I think people would have noticed by now if teachers had to conjure up a patronus every time they went into their offices. And what would happen if you were having a particularly bad day? Would you just be stuck in the corridor until your mood improved? Or —

Concentrate, Hermione! Tell it who I am, with my magic.

But who am I? Unbidden, memories rose to the surface of her mind. Eleven-year-old Hermione Granger, all hair and teeth, hand raised high enough in the air she almost dislocated her own shoulder as Snape's gaze passed over her as if she was invisible and settled on Harry Potter. Sneaking into Snape's storeroom under Harry's invisibility cloak, searching for boomslang skin. Watching in disbelief and then suspicion as Harry managed to turn out a perfect potion when her own best efforts were only quite competent.

The memories streamed past without her looking for them. It was almost, but not quite, like being on the receiving end of Legilimency. Revision, exams, brewing Polyjuice both in Moaning Myrtle's bathroom and then, later, at 12 Grimmauld Place … returning to the half-ruined school as part of the shell-shocked year of 1999, the repairs taking place around them as they slogged through their N.E.W.T.S year … the slow and painstaking research into Thief's Downfall that had won her the title of Master and the wish, over and over, that she could show her results to Professor Snape and ask for his advice …

Finally, last of all, her own hand holding a quill and signing a firm Hermione Jean Granger across the bottom of a magical contract.

Suddenly the net beneath her fingers was no longer cool and silver, but a warm golden welcome, wrapping around her as well as the room in front of her. And not just that room. The Potions classroom was part of it, too, and other places in the school — the staff room, the library —

And there, in the middle of it, a spot where she could feel her welcome should extend but didn't, a blank, like a missing tooth.

Slowly, she took her hand from the door, and it swung open. "Teachers always talked about the school wards," she said slowly. "I never really understood what that meant. I thought they were just … I mean, I thought the Headmaster set wards, and they were very strong. I didn't realise …"

"That the castle has magic of its own?" Snape said, and there was no sarcasm in his voice. "Hogwarts is very old. It was built by very powerful wizards and witches, and strengthened and maintained by many more, some even more powerful than the founders."

"Help is always given at Hogwarts, to those who ask," Hermione whispered. "I thought that meant that Professor Dumbledore was watching over us."

"And you never wondered how so many teachers managed to turn up so quickly when there was serious trouble?"

"You were all witches and wizards," Hermione pointed out a little tartly. "I, quite naturally, assumed it was by magic. I just didn't realise it wasn't just your magic." She stepped through the door and glanced around, a little disappointed to realise that the changes that Slughorn had made to the office during his tenure hadn't been magically undone with his departure. She turned back to look at Snape. "Do you need to be invited in?"

The corner of his mouth turned up a little as he followed her into the room. "I'm a former Potions Professor, not a vampire."

"Right, well." Hermione put her bag down and tucked her wand into her sleeve. Somehow she knew that there was nothing he could do to hurt her in here, not now Hogwarts itself had recognised her, even if she was horribly wrong and he was an impostor. "Would you like a cup of tea while you tell me why you let us all assume you were dead for five years?"

Snape sat down in one of the big, overstuffed chairs that had replaced the sleek black armchairs that had been in this office in his time with a precise flourish of his robes, crossed one leg over the other and steepled his fingers. Making the point that however much this might now be my office, he's not about to show me any deference about it. "Thank you. Your house elf's name is Tilney." He paused, and then added very dryly. "Try not to force any clothes on her in your first day."

"I'm not completely incapable of learning from my mistakes," Hermione snapped. "Tilney?"

The house elf appeared with the characteristic crack of apparition, and then took a step back from Hermione, hands raised defensively. "Tilney is not wanting any clothes, miss."

Oh for … Hermione shot Snape a sour look, which didn't seem to make a dent in his air of faint amusement. "I promise, Tilney, I won't give you any clothes unless you ask me for them."

"Tilney will never be wanting any clothes!"

"Then you'll never ask me for them, and I'll never give them to you. Alright?"

The house elf nodded until her head seemed to be in danger of coming off. "Tilney is very grateful, miss."

"Tilney, I'd be very grateful if you could kindly bring Professor Snape and I some tea?" Her stomach growled a reminder that she'd been too nervous for breakfast. "And a snack, please."

"It would be Tilney's great pleasure to bring tea for Professor Snape!" The elf declared, and as an afterthought, "And miss, of course."

"Thank you," Hermione said brightly. "And, Tilney, please tell the other elves that I won't try to give them any clothes, either, unless they ask me to."

"Given up the crusade?" Snape asked as Hermione took out her wand and moved Slughorn's overly-decorated coffee table closer to the chair he'd chosen.

"No." A flick of her wand and another chair slid through the air to settle across from his. "But I've realised that you can't cure a life-time's worth of magically-induced Stockholm syndrome by handing over a sock." She sat down and gave him a level stare, keeping her wand where he couldn't avoid seeing it. "Now. Where have you been for five years, and why?"

He eyed her wand. "Or you'll Crucio me until I give you some answers?"

From his expression, he didn't take the threat seriously, and Hermione knew enough about the Unforgivable curses to know why. You have to mean them, Harry always said.

"No." Hermione folded her arms. "But I might try Rictusempra." From the look on his face, Snape took that as a much more alarming prospect, and Hermione suppressed a grin. She was about to press her advantage when Tilney reappeared with the tea and a plate piled high with cakes and sandwiches. "Thank you, Tilney. These look delicious."

"They is Professor Snape's favourites," the elf said, and was gone.

"Milk?" Hermione asked, setting aside the threat to tickle him into revealing his secrets for the moments. He shook his head slightly. "Sugar?"

"Three."

Her own eyebrows went up at that, but she added the lumps without comment, handed him the cup, and picked up her own. It's not like wizards have to worry about tooth decay … although I would have picked him for black, with perhaps a squeeze of lemon. Bitter and sour, that should be how Severus Snape took his tea. "Now. We've covered how you survived. Let's get to why you've been pretending you didn't."