Harry Potter sighed and closed his eyes for a moment after his first glimpse of the Hogwarts Express, bright red and inviting, ready to take him back to school for his sixth year. The summer at the Burrow had been brilliant, but he had missed his four-poster bed in the boys' dormitory, he'd missed visiting Hagrid and he'd missed the DA.

He saw Hermione running towards him and the Weasleys, waving wildly. She had spent the entire holidays in France with her parents, so this was the first time he'd seen her since the end of the last term. Her letters had sounded very excited about his visit to Slughorn with Professor Dumbledore and she had tried to get every possible detail about their new DADA teacher out of him. There hadn't been much he could tell her.

His vision was obscured by a mass of bushy brown hair as she enveloped him in a hug. Except – it didn't seem so bushy anymore, but rather silky-soft and curly. Hermione felt – different, somehow, now that he came to think about it. She had certainly grown a lot, she was quite a bit taller than him now if he wasn't mistaken.

When she let go of him and stepped back, other changes became apparent. The phrase "curves in all the right places" occurred to him before he resolutely squashed it. This was Hermione! He didn't think about her this way, she was like a sister to him, like Ginny… Well, if he was really honest with himself, not quite like Ginny.

Hermione had already moved on to hugging Ron and Ginny. If Harry was honest, the gobsmacked expression on Ron's face was rather funny. The whirlwind that Hermione had become swept them up and whisked them away towards the train. When they had found a compartment and stowed their trunks, Hermione flopped down in a seat.

Ron had remained standing. "Uh, Hermione?" he asked. "Aren't you coming to the prefects' meeting?"

She sighed. "Must I? It's going to be so tedious."

"But you always go to the meetings. What's wrong, are you ill?" Ron sounded worried. "Please don't leave me to deal with Malfoy on my own."

Suddenly Hermione seemed to perk up. "Draco is going to be there? Of course I'm not ill. I'll go with you." And with that, she jumped up out of her seat and was out the door before Ron even had time to react.

"Well that was weird," said Ginny when Ron had hurries after Hermione. "Think something happened in France? Because she did not fancy that slimy git last year.

Harry coughed, surprised. "Fancy him? You think she fancies Malfoy? But… I thought her and Ron were… sort of dancing around each other."

"Well yes," Ginny conceded, sounding very reasonable. Suddenly, Harry felt like a child listening to a teacher. After all, Ginny had had a boyfriend, and she was a girl… Surely she knew about these things.
"Last year, they were sort of circling each other, but now? Ron obviously still likes her, but it seems like she jumped ship. Did you see how eager she was to see him? That was so strange. But yeah, she absolutely fancies him."

Hermione fancy Malfoy? It seemed almost impossible to Harry. How had that happened?

The door slid open and Neville and Luna came in.

"Hey Harry," said Neville, "Can we come sit here? There's no room anywhere else. Hey, are you okay? You both look spooked."

"Come in, we have plenty of space," answered Ginny. "Just let Harry sit there, he's not quite ready to deal with the fact that Hermione fancies Malfoy."

Neville's mouth opened and closed like that of a fish. Luna meanwhile had drifted over to the window seat and was staring out into the rain.

"Oh, has she been caught by a wrackspurt? I told her they were native to France, but I don't think she listened… Wrackspurts like yellow, maybe it's because of his hair."

Neville still looked almost as shocked as Harry felt. "Well, where is she? At the prefects' meeting? Ron will make sure she doesn't do anything foolish, won't he?"

I really, really hope so, thought Harry.

They moved on to a game of Exploding Snape, but the cards kept exploding into everyone's faces. After Harry's eyebrows had been singed off for the third time due to his distraction, he was very glad to see Ron opening the compartment's glass door. However, be became a bit concerned when he saw that Ron was alone, and scowling. Ron dropped into his seat and folded his arms across his chest, frowning.

"Uh, Ron?" Ginny asked tentatively. "What happened? Where is Hermione?"

Ron just grunted and stared out of the window.

"Do you want a chocolate frog, Ron?" Luna offered, "It's okay, I don't need it."

That seemed to wake Ron up somewhat. Still silent, he took the chocolate frog and stuffed it into his mouth in one piece. After chewing and swallowing it, he seemed marginally happier.

"Thanks, Luna. D'you want the card? It's Dumbledore again. Anyway, she went off with Malfoy is what happened. She was staring at him and sort of – sighing at him the whole time. And then after the meeting she went over to him and started batting her eyelashes at him. And then he went off with her hanging off his arm, looking at him like he hung the bloody moon. Sickening. What the hell does she see in him anyway?"

Harry felt stunned. Hearing Ginny say that Hermione fancied Malfoy was one thing, but having Ron tell them that she was actually acting on it? Hermione hated Malfoy. Didn't she?

The rest of the trip to Hogsmeade was awkward and almost silent, as no one seemed to know what to say, especially to Ron. When they had left the train and were on their way to the carriages, they saw Draco Malfoy swaggering along some yards in front of them. Hermione was following him, talking to him too softly for them to hear. As Malfoy handed her into the Thestral-drawn carriage he turned around and smirked at them triumphantly.

Harry and Neville grabbed Ron to hold him back. Neville stumbled and almost failed to catch his arm. Harry missed Hermione already. With her, this manoeuvre worked with practised ease, fast and without problems. He sighed. If Hermione really fancied Malfoy, it was going to be a long year.

Up in the school, in the Great Hall, the students were already buzzing with rumours. Harry, Ginny, Neville and Luna formed a ring around Ron and pushed through the crowd towards the Gryffindor table. Harry and Neville sat on either side of Ron with Ginny sitting across from them. Once they were seated, Luna waved them goodbye and skipped off to the Ravenclaw table.

At the last minute, Hermione slid into her seat next to Ginny, but she kept staring towards the other side of the Great Hall, to where Draco Malfoy was sitting. Ron scowled at his plate, pointedly ignoring Hermione. Not that she noticed, she was currently redoing her make-up with the help of a little mirror she had charmed to hang in the air in front of her face. Harry and Ginny exchanged a significant look. Hermione had certainly changed over the holidays.

Ginny inclined her head to point at Hermione and mouthed "Her clothes!"

She was right. Harry hadn't noticed before, but now that he was really paying attention, he saw that Hermione was not wearing her school uniform under her robes. The skirt was far too short, for one thing, and her tights were ripped. And those heels were really high… How did she even walk in them?

He would have to ask Ginny later. She was a girl, she would know about these things, wouldn't she? Harry felt that his knowledge in this area was severely lacking. He had never thought he needed to know much about normal girl behaviour, but now that one of his best friends was acting like she'd been possessed… Could that actually be the case? What if this wasn't normal, if there was something Dark going on? He would need to discuss this with Ron, Neville and especially Ginny later.

The rest of dinner was extremely tense. Everyone seemed very relieved when it was over. Ron's expression had gotten grimmer and grimmer while Hermione had proceeded to ignore the revelation that Snape was their new DADA teacher instead of Slughorn in favour of making moon eyes at Draco Malfoy, who was starting to look weirded out by Hermione's behaviour.

After dinner, Malfoy seemed to disappear without a trace. Hermione looked around and then set off, presumably to try to find him again. After a short discussion among her friends, Neville went after her to keep an eye on her and if possible bring her back to the Gryffindor common room.

As soon as she had left the Great Hall, Malfoy approached Harry, Ron and Ginny.

"Potter," he drawled "how strange to see you without your little know-it-all."

"Malfoy, you git, what did you do to her?" Ron snarled. "Love Potion? Imperius Curse, huh? What was it?"

Harry and Ginny had grabbed Ron again as a precaution as soon as they had seen Malfoy approaching them.

"Calm down, Weasel. I didn't do anything to her. I was as surprised as you. I have to say, this is quite amusing, but also extremely inconvenient. I have better things to do that deal with your little mudblood. So keep her away from me." He turned on his heel and stalked off.

With Ginny's help, Harry had been able to restrain Ron when Malfoy had insulted Hermione. Now they dragged him out of the Great Hall and to Gryffindor common room. Luckily they didn't need to wait for the password, as Rib, the prefect, had been told at the prefect's meeting on the train. They sat in a group of squashy armchairs by the fire. Harry heaved a sigh. He had envisioned his first evening back quite differently.

Ginny convened their impromptu war council. "So, what the hell so we think happened? This is not normal Hermione-behaviour. I could see Lavender Brown acting that way, but Hermione? So what do you guys think?"

Harry didn't have to think for long. "I guess something must have happened in France. Because Hermione would never go for Malfoy, even if she suddenly became all … girly."

"Oh, girly?" Ginny arched an eyebrow. "Is that a bad thing now?"

"Yes, … no. You know what I mean. She's not acting like herself. Hermione is far more likely to roll her eyes at somebody than to bat her eyelashes."

"Especially when it comes to Malfoy. Do you remember when she socked him in the jaw? That was the real Hermione, not his bad copy." Ron still sounded extremely sullen.

His attitude was not helped as the portrait hole opened and Neville shepherded Hermione through. She walked straight past them with a dreamy look on her face, not even acknowledging them. She disappeared up the staircase towards the girls' dormitories. Neville joined them by the fire and they filled him in on what little discussion they'd had.

"Maybe she just changed over the holidays?" Neville offered. "We should give her a while to get back to normal."

The other three reluctantly agreed.

"We'll give her a week," Ginny decided. "Then we'll confront her about it."

Still feeling somewhat disturbed about the change in their friend, Neville, Ron, and Harry retired to their dormitory. No matter how strange the outside world got, the room's warm colours and comfortable, familiar four-poster beds could always make Harry feel better, and he soon fell into a dreamless sleep.

Over the next week, Hermione continued to behave bizarrely. She barely raised her hand in class. In Defense against the Dark Arts, Hermione had stared out of the window and not come even close to casting any spells soundlessly. Nor had she seemed to listen at all to Ron and Harry's outraged complaints about Snape. In Potions, she had not identified any of the potions Slughorn had shown them. Her Draught of Living Death had been atrocious, and she hadn't seemed to care that it had been Harry who had won the Felix Felicis and not her.

Finally, in Transfiguration, she had completely failed in the task that Professor McGonagall had set them and even talked back to her when she had questioned Hermione's new work ethic. Apparently, their Head of House was "an ugly old hag who had never been in love and wouldn't know love if it bit her on the arse." Harry had never seen Professor McGonagall go so red or her mouth so narrow. Hermione now had a week's detention.

The entire week, she had seemed a world away, except when she had had Draco Malfoy in view. Then, she became intensely focused on him. Malfoy himself had become extremely irritated with this behaviour. He kept glaring at them all and muttering about mudbloods and blood traitors, except when they were within earshot of the teachers. Yet whenever dinner was over, he fled the Great Hall to the Slytherin common room, where Hermione could not follow.

On Saturday, Harry, Ron, and Ginny cornered their quarry in a window seat in the common room. "Hermione?" Ginny asked tentatively. "Can we talk for a moment?"

Hermione nodded and kept on chewing her bubble-gum. She wasn't wearing her uniform, but rather a blood red miniskirt, a very low-cut top advertising some band Harry had never heard of, and a studded leather collar around her neck. Over the holiday, she seemed to magically have acquired a tattoo of an ornate cross on her left wrist.

Not looking up once, she continued doodling variations of DM+HG and Hermione Jean Malfoy on her parchment, liberally decorated with little ink hearts.

"Hermione, don't take this the wrong way," Harry continued after Ginny glanced at him helplessly. "We've all noticed you have been acting strangely the last week."

Still no reaction from Hermione.

"Especially when it comes to that git Malfoy," said Ron accusingly.

Instantly, Hermione seemed to wake up and rounded on Ron.

"Like, don't even call him that!" she shouted. "He's like, so much better than you! Just look at his sexy hair! And he totally loves me too, I can see it in his eyes! So much passion!"

"I think that's actually revulsion," said Ginny, "let's go, this isn't getting us anywhere."

They all headed back over to their own group of armchairs.

"So what do we think?" asked Ginny. "Possession? Imperius?"

"Why would anyone want to Imperius Hermione to be like that?" replied Harry.

"Malfoy might," said Ron, venom in his voice.

"But why?" asked Harry. "Besides, he seemed to think that this is just as weird as we do. He keeps running the other way whenever he sees her."

"Exactly," Ginny agreed. "And what else would be the point? I think possession is the most likely option here. Do either of you know anything about that? I really only have experience with Voldemort in that department."

Harry and Ron exchanged a look and indicated that they didn't know anything relevant either.

"Okay. Then we'll meet up here tonight, do some research in the Restricted Section. For now, I already have a mountain of homework from Snape, and I'm sure you do too."

Harry had to admit that he did, too. He was very impressed with the way Ginny had taken charge of everything. If he and Ron had had to deal with this on their own, he had the feeling there would already have been fights and they would still have been floundering in the dark. Now at least they had a plan of action.

He sighed as he unrolled the parchment for Snape's essay. This was not going to be easy. As he was trying to come up with ways to lengthen his essay, he found that he was distracted by everything.

The staccato beat Ginny was tapping out on the table with her fingernails, the glint of the setting sun on her bright red hair, and the way she kept biting her lip in frustration. He gave up on the essay altogether and simply watched Ginny write hers, his head resting on his arms.

Some time after midnight, Harry and Ron went back down to the common room. Ginny was already waiting for them by the portrait hole. Climbing out into the corridor with the three of them covered by the Invisibility Cloak was difficult, but they managed without too much of their ankles showing.

With the help of the Marauder's Map, they made it to the library without running into anyone.

The TARDIS wheezed as it came to rest on the stone flags in the Great Hall of the castle.

Rose wasn't quite sure where they were. They had been following an escaped Mar'su from the planet Tootram'su. These aliens liked to possess humans and twist them completely out of character. They had to find it, catch it, and return it to its home planet before it caused too much chaos.

Being possessed by a Mar'su was no joke. The person being possessed was aware the entire time, trapped in their own body, unable to prevent the Mar'su from doing whatever it liked with it. So here they were, in a draughty castle somewhere in Scotland, sneaking about at night.

Rose was already admonishing the Doctor for this, why had he landed them here at night? They weren't going to catch anyone acting strangely in their sleep… For now, they were simply looking around the castle, trying to get a feeling for what sort of a place this was.

They were passing by long rows of suits of armour, wandered past what looked like a classroom with a sign reading "Transfiguration" on the door, and were now quite sure that this was not a normal castle.

Next, they stumbled upon a large library. "Good," said Rose, "we can check out the books, maybe they have a brochure about this place."

Without argument, the Doctor gestured for her to precede him into the long, high-ceilinged room. They skirted the ends of the long shelved, labelled "Dragons", "Charms", "Potion-making" and similar magic-y things. They reminded Rose of fairy tales she'd heard when she was little. Those had always bothered her somewhat, as she didn't agree with the view that the Princes always rescued the Princesses, never the other way around.

Finally, they reached the end of the long rows filled with ancient tomes and reached a part of the library that was divided from the rest by metal bars, marked "Restricted Section".

"Ah," said the Doctor with a grin, "our kind of section, do you reckon?"

"Absolutely!" said Rose with an answering smile.

They sneaked through the gate with as little noise as possible. They had just closed it behind them when they heard quiet footsteps and saw, to their surprise, three pairs of feet walking ahead of them – three pairs of feet without bodies attached to them.

Harry, Ron, and Ginny had just reached the Restricted Section safely and relaxed a fraction when they heard someone cough delicately behind them. All three froze immediately.

"We can see your feet, you know," said an amused woman's voice behind them.

The jig was up. They turned around and Harry whipped the cloak off of them, cursing their bad luck. If Ron wasn't so bloody tall… Well, no use blaming him. They he realised that he had never seen the people grinning at them in his life, and by the looks on their faces neither had Ginny or Ron.

"Hello there!" said the man standing next to the woman who had addressed them. He was taller and more menacing-looking, but grinning no less widely than his friend. "This is Rose and I'm the Doctor. Any who are you?"

There was a certain amount of shuffling of feet and sideways glances before Harry spoke. "I'm Harry and this is Ron and Ginny. What are you doing at Hogwarts at this time of the night?"

"I could ask you the same thing! Answered the blonde woman. Her name was Rose, Harry remembered.

"We go to school here," said Ginny, rather confrontationally, her Weasley temper showing through her calm façade. Her hand was inching towards the pocket her wand was poking out of. "Whereas we've never seen either of you here before, so you'd better tell us before I decide you're both Death Eaters."

"Death what?" Rose questioned. "That sounds disgusting. We're just passing through, looking for a bit of an escapee."

"You wouldn't happen to have seen anyone acting wildly out of character, would you?" the Doctor added.

"Yeah!" said Ron desperately. "That's why we're here, looking up possession. Do you know anything about that?"

"Well, well." The Doctor turned towards Rose, talking to her as if the others weren't even present. "That was easier than expected."

"Yeah, I would have thought teenagers would be harder," she answered, completely ignoring the three teenagers standing in front of her. "What with mood-swings and drama and whatnot."

"So!" she turned back towards Harry, Ron, and Ginny. "Who's that friend of yours and how are they acting out?"

It was a mark of their desperation that the three immediately began divulging information to these virtual strangers.

"Our friend Hermione–" Ginny began.

"Hermione Granger." Ron interjected.

Ginny glared at him. "AS I was saying, Ron, our friend Hermione has been acting extremely strangely since she came back from the summer holidays. She looks different, for one thing, her hair used to be completely unmanageable but now it just does whatever she wants it to –"

"And she's dressed differently," added Harry, "normally she'd never wear anything other than her school uniform during lessons, and she's not participating in class, and she's talking back to the teachers, she's suddenly got a tattoo she'd never get – "

"And she's suddenly fancying that wanker Malfoy!" Ron concluded furiously.

"And her not taking part in class or liking this guy is so weird?" Rose asked sceptically. "Couldn't she just have other things on her mind this year?"

"No." said Harry emphatically.

"They hate each other," Ginny added. "A couple of years ago she punched him on the nose. And he calls her there really awful slurs and constantly insults her friends. It's really impossible that she'd suddenly ignore that and throw herself at him. He's not even good-looking! Rat-faced little twit."

Rose looked sympathetic. "All right," she answered Ginny. "If you say it's impossible. She's your friend, you'd know best. So where is she? We have to get that thing out of her as fast as possible."

"We left her in our dormitories," Ginny said, "I checked on her just before we left, she was asleep."

"All right then," the Doctor said with a manic grin, "lead the way!"

They had sneaked back through the castle and were now standing at the foot of the stairs leading up to the girls' dorms.

"So boys literally can't get up to the girls' dorms?" Rose asked incredulously. "How?"

"Magic." said the three Gryffindors in unison. It had been their answer to a lot of Rose's questions, and there had been quite a few. She was very curious about Hogwarts and their lives there, and neither she nor her companion had seemed to be bothered by their possibly being discovered where they shouldn't be.

Now the five of them were contemplating the problem posed by the stairs. In the end, it was decided that Ginny and Rose would go up to the sixth years' dorm and fetch Hermione to the common room, where all of them would try to get rid of the Mar'su Rose and the Doctor had told them about. It wasn't the most detailed plan, but it would have to do.

A few minutes later, Ginny appeared at the top of the stairs, leading a protesting Hermione by the hand. She was wearing the shortest possible negligee and had rollers in her hair. Hermione was telling Ginny off for interrupting her beauty sleep while Rose trailed behind them, looking bemused. When they arrived at the bottom of the stairs, Hermione greeted Ron and Harry with only a surly look and squinted suspiciously at the Doctor.

"Ugh, what even is this about, Ginny? I was totally asleep and, like, rejuvenating my skin and stuff."

The Doctor stepped forwards and looked her square in the face.

"In the name of the Shadow Proclamation, I order you to relinquish this host body and return to Tootram'su."

Hermione jerked back in surprise and started whining. "But, like, I was doing so well at blending in and this place is so much fun. This is so unfair!" Then she stomped her foot and crossed her arms over her chest. Harry hadn't thought that anyone other than Dudley actually did that in real life.

"Tough luck," the Doctor told her. "This body already has an owner, and you were doing a terrible job blending in. These three had you pegged within moments of meeting you!" He rummaged around in his coat and produced an object that looked like a short, thick wand with a blue knob on the end.

When she saw it, Hermione, for the first time, looked frightened instead of merely inconvenienced. "Please, no!" she begged the Doctor. "Tootram'su is so boring, and there aren't any cute blonds to play with. I won't let you take me back!" She walked backwards until she reached the window, then quickly opened it and jumped up onto the ledge. "See if you can do anything with what's left of her if you force me out!"

The Doctor and Rose stilled, then drew closer together with Harry, Ron, and Ginny.

"You guys have magic," she whispered out of the corner of her mouth. "Can you save your friend if the Doctor gets that Mar'su out of her? We brought the stuff we need to catch her once she's out."

"Yes," Harry answered her, "Ron, Ginny, you get her with Wingardium if she falls, but I'll try to bodybind her where she is. If I can't I'll conjure a cushion at the bottom, but I think levitation is our best bet. Agreed?"

The others nodded their assent. Ron and Ginny started inching forward while Rose got something very much like a cross between a vacuum and a butterfly net out of her backpack.

The Hermione-impostor seemed threatened by it and now held on to the window precariously, almost hanging out.

"NOW!" shouted the Doctor, then he pressed a button on the metallic wand and it started to hum and vibrate. A terrible scream ripped from Hermione's throat, but then a sort of silver mist streamed out of her mouth and nose and her body crumpled.

"Petrificus Totalus!" Harry shouted. He hit Hermione square in the chest, but her fingers had already let go and she toppled backwards out of sight. Ron and Ginny sprinted forward, closely followed by Harry. Thanks to their long practise with Dumbledore's Army, they were used to working in concert and none of them got in the others' way.

When Harry reached the window, Ginny and Ron had already stabilised Hermione's rigid body with their levitation charms. Harry added his own "Wingardium Leviosa!" and together they guided Hermione back through the window.

Once she was safely back inside, they turned around to see pandemonium before them. Rose and the Doctor both had butterfly nets and were chasing the silver mist that had been insider Hermione around the room. The Gryffindors conjured streams of air to keep the Mar'su from escaping, but the measure turned out not to be necessary. Rose darted forward and her butterfly net sucked up the silver mist. Once it was all inside, she and the Doctor turned off their contraptions.

"That's that done." Said the Doctor, wiping sweat from his forehead.

"Is she okay?" asked Rose, gesturing towards Hermione.

"She seems to be," Harry said, removing his petrification spell. Ron laid Hermione on the sofa in front of the common room fire.

"Well, it has been lovely, but we must be off." The Doctor patted Rose's butterfly net. "We'll have to get her back to her home planet."

"And good luck with your friend," added Rose. "It's not going to be fun when she wakes up and remembers what she's done. Well, at least not for her, it may be great fun for you!" The two of them sauntered out of the Gryffindor common room arm in arm.

Harry, Ginny, and Ron watched them go, then sat around Hermione's unconscious form, watching over her and debating what aspect of her transformation would mortify her the most.