She turned in a circle. "Professor Snape?"

Oh, Merlin's pants, he can'thave been so stupid as to go outside …

"Professor Snape?"

There was a closed door on the other side of the room, between two of the towering bookcases. Hermione frowned. Was that there before?

It must lead to …

'Professor Snape's bedroom' sounded bizarre, even inside her own head. Hermione snorted at her own silliness. What, did you think he slept hanging upside down, like a bat? Thinking back, she realised she'd never thought about it at all, as if Snape had never existed except as a teacher and a spy, and, those duties done, had evaporated into a swirl of black smoke until called on again. Really, she'd thought of all their teachers like that: the idea of Filius Flitwick in a nightshirt, or Minerva McGonagall clipping her toenails, had never entered her head.

But, of course, they had all had beds they slept in, and bathrooms to brush their teeth in, and private lives entirely separate to their existence as teachers, Severus Snape included. They'd gathered in the staffroom and talked about things that interested them, and played chequers if Flitwick was to believed. They probably read unlikely things, just because they enjoyed them — the way Hermione read the novels of Elizabeth Gaskell and Harry and Ron went to every film with a superhero in it, and then spent hours arguing over whether Superman's powers were a Muggle interpretation of magic or not.

Professor Snape no doubt had his own taste in literature, and perhaps other hobbies as well, although Hermione couldn't imagine them. Knitting seems extremely unlikely.

Although if he'd found teaching as exhausting as she had found it today, he'd probably retired to his private rooms and been content to slump in front of the fire and stare blankly at the flames.

At least the existence of other rooms — and I should have realised there would be, if Snape asked the Room to give him somewhere to hide indefinitely — meant that Snape hadn't necessarily gone outside. He's probably just sleeping. He's been here for a week, after all, with no natural light. His circadian rhythm is probably completely messed up.

Still, she had to be sure, because if Snape was wandering around, she had to go straight to Harry and … either tell him I want to borrow the map so he doesn't get a chance to spot Snape on it, or else ask to look at it with him and hope he does spot Snape on it.

After all, she'd promised she wouldn't tell anyone.

She crossed to the door and knocked. "Professor Snape?" No answer, and she knocked more loudly. "Professor Snape?"

"Go away." Coming through the door, his voice was muffled.

Not sure if she was relieved or disappointed he was still safely hidden, Hermione raised her voice a little. "Professor Snape, I wanted to ask you —"

The door flew open so suddenly that she took an involuntary step back. Snape stood with one hand on the door frame and the other gripping the edge of the door as if preparing to slam it closed again. "Did you not hear me?" he said with icy disdain. "I don't want to listen to you wittering on about your well-founded doubts and fears about your teaching at present, Granger. Go. Away."

Hermione drew herself up. "Actually, my classes today went very well, thank you."

"Fascinating," he sneered. "Now you've mastered teaching, try working on your comprehension of the English language. The words 'go away' are generally taken as an instruction to leave. To get — " His hand slipped on the door-frame and he lurched sideways, shoulder hitting the jamb. "Out."

Hermione looked at his drawn face and realised Snape hadn't been getting ready to slam the door in her face. He was holding himself on his feet. With a flick of her wand, she drew the nearest chair from the fireside to the doorway. "You need to sit down."

"I need whatever Potter left of my privacy respected," Snape hissed, but he grabbed the back of the chair, bracing himself with a white-knuckled grip.

"Professor — if you're ill —"

"Granger." He spoke between gritted teeth. "Take your buck-toothed, bushy-haired, busy-body self out —" His knees buckled and he caught himself across the back of the chair.

"Sir!" Hermione cried, reaching for him.

Snape flinched back from her, raising his head, his dark eyes looking past her at something in the distance. "I — made the — right — choice," he gasped, and then his eyes rolled up and he went limp.

"Mobilicorpus!" Hermione snapped instinctively, and caught him before he hit the ground. Thinking better of the chair, she moved around it, raising Snape a little higher from the floor and floating him before her as she stepped into his bedroom.

She spared once quick glance around the room, getting a general impression of thick rugs over a wooden floor and more bookcases, before spotting a huge and comfortable-looking bed. Carefully, she manoeuvred Snape over to it and lowered him down as gently as she could.

He lay so still, and his already-pale face was so white, that Hermione felt for the pulse at his wrist with real fear that she wouldn't find one. Take them … look at me …

Shut up! she screamed at her memory, and let out a breath that was almost a sob when she felt the faint beat of life beneath her fingertips. "Professor Snape? Can you hear me?" She took his hand in both hers. Merlin, his skin is cold. "Professor?"

He needs Poppy Pomfrey.

He needed to be in the Hospital Wing, but Hermione wouldn't give a clipped knut for her chances of levitating him through the corridors unseen. Sending a Patronus to tell Madam Pomfrey she was needed wasn't exactly discreet, either. She could just imagine her little otter sitting up on hind legs in the middle of a crowd of students and blurting out that she was needed in the place Severus Snape is hiding …

"Tilney! Tilney, I need you!"

No whip-crack of apparition. The Room must defeat even a house elf's magic.

She could go and get Madam Pomfrey herself, but what if Snape woke up while she was gone? In the mood he's in, he might tell the Room not to let me back in.

She closed her eyes and concentrated. Room of Requirement, I need … things to help Professor Snape. Whatever that might be.

When she opened her eyes, there was a small table beside the bed. A basin of water and a cloth were on top of it, along with several vials.

They were probably safe, given the Room's properties, but Hermione was still reluctant to tip unknown potions into an unconscious man. She dipped the cloth in the warm water, wrung it out, and sat on the edge of the bed to wipe Snape's face. "Can you hear me, Professor? The Room has brought me potions for you, but I don't want to give them to you without knowing what's wrong with you." Relaxed in unconsciousness, Snape looked both sicker and younger than when he'd been looming over her, dark eyes glittering with fury. But then, he isn't all that old, is he? The same age as Harry's mum would be. Funny to think that, when for all her school years he'd been just the same indeterminate eternal age as all the Professors had seemed to be. If I'd been told, at eleven, that Professor Snape and Professor Dumbledore were the same age, I wouldn't have found it at all unbelievable.

She moistened the cloth again. "I don't know why you didn't just stay in bed and tell me to fetch Madam Pomfrey. That would have been the sensible thing to do. Instead of collapsing all over the place." I need whatever Potter left of my privacy respected, he'd said. "I suppose you didn't want me to know, did you? I probably wouldn't want you to know if I was sick. I'd like to think I wouldn't be this silly about it, though. What if I hadn't caught you in time? You could have hit your head." Brushing his cheek with the back of her fingers, Hermione was relieved to find a little warmth. "That's better. Can you try and wake up for me, Professor Snape? Please?"

His eyes opened slightly. "Will it shut you up?"

Hermione smiled with relief. "There are some potions here. The Room brought them. I suppose potions aren't included in the exceptions to Gamp's Law —"

"So the answer is 'no'," Snape said wearily. He raised himself on his elbow, and from the tightening of his mouth, Hermione guessed the movement hurt him.

"Let me," she said quickly, and Summoned the vials to her hand. She held them out. "Here."

Snape took them, the potions shivering in their bottles with the tremor in his fingers. "Your curiosity about Gamp's Law and its exceptions must remain unslaked. The Room has merely relocated these from my workroom." Slumping back to the bed, he took all three, one after another, grimacing ferociously at the taste of the last one. After a moment, a little colour came back to his face. "There, Granger. Your mission of mercy is now complete. You will find the door behind you."

Hermione didn't move. "I'm not leaving until you promise me you won't make yourself unfindable when I come back with Madam Pomfrey."

Snape sighed. "There's no need and less profit in troubling Poppy. Anything she can do for me, she has."

Hermione frowned. "But you're not better? What about St Mungo's?"

"I cannot avail myself of St Mungo's, for obvious reasons."

"That's not very Slytherin of you," Hermione said robustly. "Aren't you all supposed to have a well-developed streak of self-preservation?"

He flinched. "You've found me out," he said harshly. "I'm a very poor Slytherin."

"Or you already think they can't help you at St Mungo's," Hermione guessed. Snape shot a sharp glance at her, and she knew she was right. "There have been medical advances over the past few years, you know. New healing potions and salves …"

"I do know, Granger, and rather more than you, I know what they are." He scowled at her. "There must be something I can say that will persuade you to leave. Me. Alone."

"Yes," she said promptly. "You can tell me what's wrong with you, and I'll go." To the Library, to find out how I can help.

"You are the most infuriatingly inquisitive individual it has ever been my misfortune to encounter," Snape spat at her.

"And you are the most foul-tempered, disagreeable and downright rude person I've ever met," Hermione snapped. "But I don't care how much you insult me, I'm not leaving until you tell me what's going on."

"Fine," he said. Pulling up his left sleeve, he turned his arm over to show her —

Hermione couldn't bite back a gasp of horror. Above his wrist, where the Dark Mark had once been, was an oval of skin that was grey and withered. It looked not only unhealthy but repulsively wrong in the way Dark magical object felt wrong.

The way Dumbledore's withered hand had looked, in the last year of his life.

Hermione reached out for Snape's wrist, wanting a closer look. He pulled his arm away before she could touch him and yanked his sleeve back down. "Satisfied? Ready to leave?"

"It's a curse. Someone's cursed you."

"Five points to Gryffindor, less the three hundred you've lost your house already this evening for being an interfering busybody."

"Was it an object, like the necklace that got Katie Bell?"

He raised an eyebrow. "Yes, someone anonymously owled me a mysterious object precisely the size of a Dark Mark, and I, of course, thought it would be an excellent idea to press it against my skin."

It was an absurd mental image, and Hermione couldn't help but smile. "Of course not, but it could have been a watch or something."

"It wasn't."

"Well, then, the curse has been placed on you."

"Obviously," he drawled contemptuously.

"And since it wasn't the Headmistress, or Madam Pomfrey — or me — then someone else knows you're alive."

"Odd as it may sound, I had worked that out." He raised his arm a little, although the curse was now hidden. "As fascinating as it is to hear your, and I use the term loosely, thought processes, allow me to abbreviate this … invigorating … discussion. The curse has been placed on my Dark Mark. Since, I assure you, no-one has had the opportunity to do so personally, the only possible conclusion is that it was placed from another Dark Mark."

Hermione blinked at him. "By another Death Eater."

He gave a minute nod. "Or someone who has access to one."

"But all the Death Eaters are in Azkaban."

"I'm not," Snape pointed out.

"All the real Death Eaters —"

"Lucius Malfoy isn't. Nor his wife. Nor his son."

"The Malfoys were as glad to be shot of Voldemort as anyone, by the end," Hermione said. "They wouldn't be trying to get revenge. Someone must be using them — which means they'll know who it could be — which means we can find out, and make them lift the curse."

"It isn't being done by means of the Malfoy's marks," Snape said wearily. "That was my first thought, and Minerva's. I mention them only as examples of the Ministry's lack of thoroughness."

"But —" Hermione stopped as a chilling thought struck her. "Professor, I thought the Marks only answered Voldemort. For him to call people, or for them to summon him. If someone is reaching Dark Mark to Dark Mark — does that mean he's …. he's back?"