Disclaimer: The story isn't mine, it is originally written by Erised Black and the story it's in Spanish, I only translated it into English (as good as I could, I'm Spanish after all, so if you find any mistake, please say it to me!). I do not own the characters either, the ones you may know are all from J.K. Rowling, and the ones you don't know, are from Erised Black. The title in English is "I solemnly swear that I am up to no good" but I preferred to leave the title in Spanish inside the fic, I hope you don't mind ;).

Juro solemnemente que mis intenciones no son buenas

Mary Macdonald

The arrival of December brought to the school a wind wave that in Mary's opinion was Antarctic, Polar, Siberian and Canadian mixed with a jinx that made it even colder. Fuck, it sure was cold!

The blonde girl was jumping in front of the heater in the girl's bedroom of Gryffindor which was almost empty. Almost empty because her red-haired friend Lily Evans was sitting in front of her desk trying to finish the Potions' homework, but the constant movement of her friend was starting to bother her a lot.

'Mary, please, could you just stop jumping?' her friend begged turning around and leaving the feather she was writing with on the table. The blonde girl stopped immediately. It was better not to make angry the lioness, but she was brave and had a better idea. She smiled maliciously.

'Evans…' she whispered in a wicked tone, sitting on her friend's desk and crossing her legs sensually. 'I've got an offer that you can't deny.'

Her friend sighed resigned.

'Alright, tell me' she encouraged her, being a little bit funny.

Her friend's smile enlarged exaggeratedly before announcing with emotion and fastness her answer:

'I want you to tell me what the hell happened with Potter!' she began. 'The other day you were about to tell Marlene! Tell me, please!' she begged, kneeling down in the floor and putting her hands together while she made a pout worth an Oscar.

The red-haired girl faced again her homework.

'Never' she sentenced, taking again her feather scribbling furiously on the parchment.

Mary didn't give up.

'As you wish…' she nodded while starting to jump again, singing and whistling aloud, running across the room and jumping on the bed as a monkey.

Lily got up, furious.

'If I tell you, you promise me you'll go away from this room for the next two hours?' she roared really angry.

Mary stopped immediately, which made her to almost fall from the bed. She sat down and looked at her friend with a very innocent face and waited patiently. Lily sighed and lied down on the bed in front of her friend. She put her hands on her face and sighed again.

'Nothing happened' recognized the red-haired.

Mary froze.

'Nothing happened?' she exclaimed, disappointed. 'All that mystery for this? For nothing to happen?'

'Absolutely nothing!' recognized Lily, also disappointed.

Her friend that had known her for seven years now, noticed her tone. She had heard it three times: When she didn't get the best mark at the O.W.L.S., when her sister decided to stop talking to her definitely, and when she got punished for losing her mind in a Transfiguration class in which, for not being able to transfigure a dish in a bag, she transformed in seaweed the hair of a Slytherin boy who had laughed at her.

'And that fucked you up' her friend went on, perceptively. 'Will you tell me exactly what happened?'

The red-haired nodded.

Apparently, James Potter appeared in her house without any previous warning on a summer day. Lily, thinking that it was her sister, who had just left, that had forgotten her keys, opened the door; if she had checked who it was, which she always did, she wouldn't have opened the door and she wouldn't have been feeling disappointed from that bloody afternoon until now.

She let him in, she wasn't that rude as not to let him enter, but she only gave him a minute to explain himself. James was clear and precise: I'm sorry for how I've been leading with things until now. I'm not going to harass you any more; sooner or later you'll realize we're made for each other.

She got angry. How could he be so stucked up? She tried to throw him out of her house. But there was something inside her that asked her not to do it, something that was trying to make her ask him to stay in for the rest of the afternoon, with her. He had been vain, but he had also said something she had never before heard him say: I'm sorry.

Unfortunately in that very moment she knew that he was a bit, maybe just a bit, right. Not with being made for each other, of course, but yes in that if she gave him an opportunity she could end up liking that vain player of Quidditch. Because that "I'm sorry" was clearly a change in James Potter. It was a big change in his housemate.

Youshouldgo, she had said to him, finally, with a small voice.

James smiled, maybe feeling proud of him, maybe being conscious of that his words had touched deep the red-haired girl. He accepted an appropriate retirement of the enemy's territory, but he promised to come back if some day she needed his help. For whatever it was, even if it was illegal, dangerous, nearly deadly and very, very stupid.

'Oh…' Mary sighed. 'James's a sweetheart actually.'

Lily raised an eyebrow, bothered. Maybe jealous?

'You can have him to do something illegal, dangerous, deadly and stupid' she replied imitating the guy's voice, turning to face her desk again. 'I don't give a damn, honestly.'

Mary laughed, amused by the reaction of her friend. Yes, that was a hint of jealousy. Sometimes Lily was more transparent than a soap bubble.

'I take note of that' kept saying the blond girl, bothering her friend to make her confess.

Lily answered without turning away from her homework, but her friend could see that she wasn't writing anything anymore even though she was holding the feather strongly.

'Maybe you'll have too much, between Potter' she made a brief pause 'and Fabian Prewett' she went on, remarking on purpose every letter of the name.

Mary got annoyed.

'You know what? I'll let you doing your homework and I'll go to refresh myself a bit, because I can't breathe with so much jealousy on the air.' She announced, really annoyed, slamming the door after her.

She didn't want to hear anything about Fabian Prewett.

On her way to the library she came across with Remus Lupin, with whom in that moment she was talking about the latest news on the Prophet's morning: Some Death Eaters had been arrested in a special mission. Even though they didn't belong to the most important group, it had been great news. Apparently after a hard examination, they told a list of the possible victims of Lord Voldemort, but the newspaper didn't say anything else.

'I honestly think that this will only make things worse' Remus recognized.

Mare got disconcerted and he, reading her face, answered her silent question.

'They have fucked up their plans and if I was one of the Aurors that participated on the mission, I'd already be hidden in the Amazon with my family and any other important person for me.' Answered the boy 'even though that wouldn't be very useful… remember the Andersons…' both of them got pale when remembering the incident.

They were only a few meters away from the library's door when a voice that she knew well called her from the beginning of the corridor.

'Oh, no' she sighed while trying to ignore the call, but Remus had turned over, innocently, to see who was calling.

Mary didn't want to be rude to Fabian Prewett but she had started to think that it would be the only solution with the guy.

'Hi, Prewett' she greeted him when he arrived to her side.

'I've told you thousands of times to call me Fabian' he reminded her with a smile. 'Hi, Lupin' he greeted without so much happiness before turning to face the Gryffindor girl, without noticing that Remus hadn't answered him. 'Going to the library?'

Suddenly, Mary had a wonderful idea. She held Remus' hand and got extremely near him. For the first time she noticed that the boy was taller than what he seemed, maybe due to his thinness.

'In fact, my sweetie and I, just changed our minds' she announced with a sickly-sweet voice. 'Right, darling?' she winked at Remus quietly, who changed his expression of confusion for a surer face, he played his part as a good Marauder, and put his arm around her shoulders.

'Of course'

Fabian Prewett was stunned. But as a great Ravenclaw, it wasn't long until he started to mistrust.

'You're awful actors' he laughed.

Mary raised an eyebrow, turned to face Remus and the kiss was so real that even Mary was surprised. Where did that passion come from? In fact, she even forgot the Ravenclaw for a moment, and when she got back to reality she was in a secondary corridor still kissing with a guy that, some minutes ago, was just a good friend.

How hadn't she seen it before? And why did she like kissing him so much?

After apologizing to Remus she decided to get lost in the corridors of the fifth floor for a while. She needed to think. What had happened in front of the library? It had worked well to get away from Prewett, she was convinced, but maybe it was too convincing.

She sat on a bench of stone that was under some window and took out a book.

Although it was getting dark, she thought, if someone passed by he or she would only think that she was reading under the sunlight. At least they wouldn't think that she was a crazy depressed girl that was alienating herself.

She checked mentally her last meetings with Remus; on the last weeks she hadn't noticed anything weird, actually, they had barely meet outside the class due to the homework and if they had been together it had precisely been for that.

She heard some steps a little bit away from her, someone was coming close. Two persons, as she overheard a conversation.

'You can't be near me' someone demanded, a boy, to his companion.

Mary, with pure lioness intuition, deduced that it was a private conversation so, as quietly as she could, got hidden after a column that was in the dark.

The voices and the steps kept coming close, slowly, at the place where she was hidden, and she hoped that they didn't find her: for a girl hidden beside a column it was way too suspicious for being normal, and she, that hated gossip, didn't want to be the center of one.

'Oh, come on' answered a girl's voice. It sounded very childish, so she deduced that it was someone younger. 'You've done millions of favours to me since the course started. If you tell me that you don't want to be my friend, and in fact, you don't want to talk to me anymore, at least tell me why.'

They stopped. The blond girl thought that maybe in front of the column where she was.

'No' he answered, curtly and kept walking on. 'It's better for you to get away, for sure. It can be dangerous for you. Believe me.'

'Please!' she begged, following him.

Mary leaned out after the cold column. If he had had the hair a little bit longer, she would have bet that that guy was Sirius Black. But his voice didn't resemble.

'Regulus Black!' the girl shouted, when the boy started to run. 'Stop it!'

Mary understood it and she also recognized the girl. If she wasn't wrong, she was called Vance and it was from Hufflepuff. What were they up to? What was worrying so much the young Black?

She decided to go back to the Common Room to tell Lily. She didn't like gossips, she had to recognize it, and that couldn't be considered a gossip but a secret that the young Slytherin tried to hide. But why so much interest in leaving the Hufflepuff girl aside of it to protect her?

…

When she arrived to the Common Room everyone had already had dinner. As she wasn't hungry, she had wandered for the corridors a little bit longer and had been thinking about all that had happened that long day of December.

When she entered in the Common Room, full of people, she noticed that lots of eyes were looking at her, and little by little, more and more eyes were staring at her until she realized with horror that half of the Common Room was staring, pointing and whispering.

So fast had spread the rumor of the kiss with Remus?

She looked for Lily that for Mary's horror was sitting in the same table as the four Marauders. She approached her without looking at any of the boys and sat down with her head down trying to hide her blush, though it was impossible.

'Lily…' she whispered. The four boys were pretending that they were talking about Quidditch, but the blond girl knew perfectly that they were listening to what she was saying.

'Later, later…' answered Lily as she had thought the same as her friend. 'Where have you been? I haven't seen you at dinner time' she went on, talking as low as she could.

It was then that Mary came up with a great idea to evade a possible future talk that the boys could participate in. She raised her head, thinking about something else and less blushed, and looked for her housemate's grey eyes.

'Black' she called, leaving the others disconcerted. 'Your brother is up to something.'

After saying those words the boys insisted, until they got their aim, in the girls coming to their bedroom. Lily didn't want to go because "it wasn't right", but Mary accepted right away: anything was better than being the center of attention.

Calling 'bedroom' to the stable where the Marauders slept was a really inappropriate word: there wasn't a bed made, a pillow was missing in one or two beds, another one had two pillows, and a third one had a part of the sheets burned up; what once had been the canopies now were scratched in a tragic way or they had made a big knot with them so that the canopies didn't bother them while sleeping; and, a part from socks and dirty clothes, Lily found more than ninety sickles of silver on the floor during the time they were there and Mary was afraid of walking on something unknown that could transmit her some tropical illness.

'Have you ever cleaned up this bedroom since your arrival?' inquired the Head Girl, clearly annoyed.

The four boys laughed.

'I've proposed it more than once, believe me' Peter said, approaching to what the girls deduced was his bed and also the less destroyed part of the room.

'Peter likes to wake us up early on Sundays to urge us to clean' Sirius whispered to the girls, although he knew his friend could listen to him. 'It's a weird hobby that he has. But no one listens to him.'

'That's not true' answered Remus, sitting on his bed (the one that was better of the four).

James with a fast movement of his wand put on the sheets of his bed more or less in a decent way for the girls to sit on it, as it was the nearest one to the door and he had noticed how uncomfortable Mary was to walk forward on the room. Now she felt like in the lion's mouth for being as near of Remus. She was afraid of the conversation turning into a bad way and that they ended up making a colloquial talk all together.

Sirius seemed serious when she ended up explaining. Peter was watching him cautiously and Remus had his brow frowned. James messed up his hair (exasperating Lily a little bit) before starting to talk.

'The Slytherins are up to something' he said while his three friends nodded.

'Oh, come on Potter' Lily begun. 'You don't have any kind of premise to say that.' The four boys laughed in complicity. 'What?'

Peter waited for the agreement of his friends before speaking.

'Mary might remember' he said testing the water. 'Two years and a half ago, when Mulciber…'

The girl looked daggers at Peter. She might remember? How was she not going to remember it! She was lucky, very lucky that day: she almost died.

She was lucky that Mulciber didn't aim well and hit the wall, ten centimeters above Mary's head. It opened a hole of twenty centimeters that let you see the Forbidden Forest through it. The blond girl never wanted to ask a teacher what could happen if that had hit her head.

Gossip said that was dark magic; Lily never doubted it. What was that spell that could open a hole of twenty centimeters in the enchanted and indestructible Hogwarts' walls? No student knew it, the teachers didn't want to answer more questions, and Mulciber almost got expelled.

'Dark magic' answered Mary to Lily. 'Oh come on, don't mess with us…'

Remus made appear some parchments out of nowhere with his wand and started looking for the correct one. When he had it, he lent it to the two girls so they could read it.

In there, there was a list of names, hours, days, and always the same place: The Slytherin's Common Room.

'We watch them' explained Sirius. 'It is always at different times, different days of the week, but they are always the same ones, they even have increased, and they keep increasing.'

The girls were about to ask how they found out all that information, but James anticipated to their question.

'We won't tell you how we got it' he specified 'at least, not yet. Besides, it isn't useful, we don't know what they're up to exactly.'

'Maybe they aren't planning anything' contradicted Lily, although she didn't sound very sure. Unfortunately, she knew the aspirations that some Slytherin's students had by first hand thanks to old conversations she had with her never-again-to-be-friend Severus Snape.

'Of course' answered Mary, 'they'll all be there playing patchwork.'

Peter let out a sceptical laugh.

'You can't get in there because "that" is the Slytherin's Common Room and you are from Gryffindor.'

The four boys did all they could to restrain their laughing and looked at Lily as if she was the most innocent being in the world, trying to defend the existence of Santa Claus in front of her classmates.

'You can't explain us how you'd get in either' she whispered. Was it possible that James Potter, supposedly in love with her, couldn't confide a secret to her?

The alluded looked at her.

'We can tell you, if you promise to help us, without complaining, without protesting and until we reach the end of the matter.'

Both girls looked at each other. They were lions, curiosity won them.

'Alright' nodded Mary. 'But how do you plan to get in? They aren't going to tell any of us when they'll meet again, and even less the reason of their meetings.'

Sirius got up of his bed.

'I think I have an idea' he announced while going to his closet to get his winter cape and a yellowish and creased parchment that neither of the two girls managed to identify as anything in concrete. 'I'm going to worm it out from Winsett.'

All of them fell silent, looking astonished as Sirius put on his cape hurriedly while looking at his watch from time to time.

'From Tatiana Winsett?' asked Peter finally, who didn't seem to be very convinced of the persuasive talents of his friend.

Sirius, who had reached the door already, stopped suddenly.

'From the younger one… whatever she's called' he replied since he couldn't remember the name of the fifth year girl.

'Natasha Winsett?' inquired Lily. 'But you nearly poked her eye out with you wand the last time you two passed each other. She won't say a word.'

'Sirius has a plan' explained James as the alluded had just gone out of the room laughing at the top of his voice. 'A plan that I think you're not going to like at all, so it's better if…'

'If we don't know a thing' interrupted the red-haired girl getting even angrier. 'Well, we're leaving. When you can trust us, call us.'

The girls started the retreat from the enemy's territory to their room, feeling a little bit lonelier: they were four and they had always been four in that room. They were just the two of them and the room felt terribly lonely without their friends.

They had not reached the end of the staircase to the Common Room when they realized that the majority of their housemates had already gone to bed, as they could hardly hear someone speaking down there. The curfew had started an hour and a half ago.

'I wish Filch catches Black' whispered Lily, even knowing that that would never happen.

Mary was laughing quietly when she heard someone calling her a little bit more upstairs. She stopped suddenly without turning around and saw Lily disappearing around the corner of the staircase. Her friend wouldn't come back because, probably, she would have deduced who was calling Mary and because she wasn't there.

Remus Lupin appeared from the semi-darkness of the staircase and slowly got closer to her.

'Listen, Mary' he begun. 'I'm sorry about this morning. Now everyone thinks we're together' he laughed nervously.

'It actually is good for me, that they think that' answered the blonde. 'This way Prewett will leave me alone' she added, blushed.

Remus seemed to doubt a bit before adding:

'Great, but it'll be better if we maintain the rumor alive from time to time.'

And Mary lost her mind again.

…

Half an hour later she entered into her room.

Lily was already in her pajamas and inside her bed, and she had stolen some blankets from one of the empty beds. It was freezing cold in that room. ¡Oh! With all the horny of the last moment she had totally forgotten about the Antarctic, polar, Siberian and Canadian cold mixed with a jinx that made it even colder. Fuck, it was freezing cold! She was ashamed of herself.

Mary wasn't a girl of excesses. She had had a couple of boyfriends, but she had never been making out with them in the Hogwarts' corridors for everyone to see, let alone ending up in a sofa of the Common Room without realizing that there were second year students that run away to their bedrooms.

'Tomorrow there will be more gossip' whispered the blonde, getting in her bed without undressing herself. It was freaking cold!

The red-haired smiled to her, trying to seem happy.

Mary knew her friend was dying of envy. Had Lily ever had a boyfriend? Not that she knew, and she knew lots of things. She had met with various guys, that had given themselves the honour of saying amazing things about the date, and she had never denied it. To Lily this entire boyfriend thing didn't matter, there were more important things.

But now she seemed to have changed her mind.

'Good night' they said to each other before turning out the lights, trying not to think that, maybe near to them or maybe far from them, Lord Voldemort's followers were committing a new murder.

…

Okay so here it is the third chapter!

I am sorry it took so long for me to translate this chapter, as I said in the last one, the author is revising all the chapters and I didn't want to go on without making sure that she won't change anything more. I have also been busy with the university, so sorry for the waiting.

But how was it? Did you like it? I'm not completely sure about some expressions I used in this chapter, so if you see something weird, please tell me ;). I hope you liked the chapter. We have a couple now! Remus and Mary! Will they last? We'll see!

Thanks to all of you who read this fanfiction. I know that I am not the best one at translating but I do my best! So, thanks for all your support (even if it's silent!) :).

The next one is going to be… PeterPettigrew!

See you in the next chapter!

siesna