I've attempted to make the German included as accurate as possible, but I've only been learning it for two years and I only have two hours a week of it, so I've had to rely quite a lot on google translate. Sorry! If you don't speak German (or you don't understand my terrible Secondary school standard German) you might want to open Google Translate. Marauders era, swearing, implied Wolfstar (nothing explicit, not even stated properly).
Remus sat at the desk, nose deep into the book that had just arrived from home, 'Advanced German'.
"What'ya reading, Moony?" a lazy voice from behind him asked, dragging Remus from his lesson on using dative vs. the accusative.
"A book about the German language – you know that I'm learning it, right?"
Sirius nodded, grinning, before snatching the book.
"Ab und zu, hȍre ich Musik!" he bellowed, pronouncing almost every word incorrectly and with a heavy German accent. Remus was torn between laughing and taking the book back, wincing a little at Sirius's grubby fingers crumpling the edges of the page.
"You're pronouncing it wrong – the umlout changes the-"
"Ich bin...um...siebsehn Jahre alt!" came Sirius's garbled German response, accompanied by an innocent little smile at Remus. Before Sirius could attempt another sentence in an insultingly stereotypical accent, or Remus could demand his property back, James and Peter entered the dormitory, with Frank Longbottom behind them.
"I swear to god, Wormtail, if you ask to copy my Transfiguration homework one more time I'm going to- Sirius, what the hell are you doing with a book?" James trailed off when he saw that Sirius was standing erect in a stately manner, holding the book aloft as a great poet or literary mind would.
"Ich liebe dich! Hehe – that sounds like I said I love dick!" Sirius smirked as he spoke, but stopped when he saw the translation. "I don't mean that! I don't- oh Merlin, I don't mean that!"
"What did he say?" James asked, completely at a loss to understand what was going on. While he had walked in on Remus and Sirius playing silly buggers many times before, he'd never been this utterly confused by it before.
"He said that he loves you." Remus smiled drolly, before continuing, "I suppose I should be a bit offended, really. Just give me the bloody book back, Padfoot."
Sirius glanced down at the book for a moment, flicking through a few pages, before triumphantly replying, "Nein!"
"Give me the book, Sirius, or I swear I'll..."
"You'll what?" It was a relief to hear Sirius speaking English again, frankly – it certainly made a lot more sense than his gruff, deep-voiced attempts at German.
"I'll curse you so that you can only speak German." Remus grinned, very glad that the language books came with a whole list of spells usually only used by German witches and wizards printed in the back: one was given when people were so shocked they were unable to speak, and it came with a clear warning that when cast on people who's first language wasn't German, they would be forced to speak German for at least 24 hours until the initial spell wore off.
"You wouldn't dare, Moony – you of all people wouldn't dare." Sirius didn't hand back the book, and merely continued with his dramatic pose, well aware that all four of the other boys were captivated by his speech.
"Sie nicht schockiert sein, einfach glücklich sein - beginnen Sie zu sprechen deutsch!" Remus recited, all too glad that he had memorised the sentence and the little wand-flick that accompanied it. Sirius gave an odd little gasp like a fish, before cautiously opening his mouth and trying to speak. A garbled 'Blehuhu' noise escaped, followed by a single word,
"Scheiße!"
James lay on the floor, clutching his stomach with laughter, while Peter and Frank were holding tightly onto each other on the bed, both shaking violently with mirth. Remus was crying, unable to form a single word. Sirius, meanwhile, was stomping around the room, sentence after sentence of enraged German pouring from his lips like water bubbling over in a kettle. No matter how hard he tried, he couldn't get out a single word of English. He could understand English perfectly, still, just not speak it.
"W-what's he saying?" James asked, spluttering as he spoke.
"He says that your eyes are beautiful in the moonlight." Remus replied solemnly, a breathy laugh pounding even harder out at Sirius's angry exclamations and explanations for his speech. "He says that they're really quite delightful."
Sirius's fist flew out and thumped Remus on the head, sending James, Peter and Frank into another paroxysm of laughter.
"Ich hasse dich!" Sirius growled, staring at Remus with the expression of a rottweiler that had just been stamped on.
"Love you too, mate." Remus cheekily replied, finally taking his book back from Sirius and giving him a little wink. That was too much for long-suffering Sirius, who suddenly ran at Remus, knocking him from his chair and kneeling on his chest. The string of German that escape Sirius's lips wasn't translatable, but Remus could get the general gist of what he was saying, which made him laugh harder. The next thing he knew, Sirius turned to Padfoot, and Remus's emotions changed slightly as he stared up at the huge, shaggy black dog.
"What does a German dog say?" James asked, smiling.
"Dachshund!" Remus replied, accepting that their shared, terrible pun was totally worth a scrap with a dog for.
"Sirius, what's the answer to question six?" Professor McGonagall asked the next morning, smiling. While the four boys known as 'the marauders' happened to be totally irresponsible and mischievous, all were good students, with Sirius, Remus and James shining especially. So far, Sirius had avoided talking, keeping his lips tightly closed throughout breakfast and the first lesson (Potions) except for one attempt to speak English which ended in another wrestling match with Remus.
Sirius shrugged, staring down at his parchment and bottle of ink.
"You must know, Black – come on, tell me."
"Drehen Sie Ihr Handgelenk und dann blättern sie." Sirius very quietly replied, glaring down at the English words written and trying hard to say them, and then growling at the sound of the German sentence. As soon as he could speak English, he was going to kick Remus's arse, if not before.
"What did you just say?" Professor McGonagall asked, rather taken aback at what sounded like fluent German coming from Sirius. Was it some kind of silly prank? The grins on James, Peter and Remus's faces certainly suggested so, but Sirius himself looked angry rather than amused, and rather downcast on top of it.
"Drehen Sie Ihr Handgelenk und dann blättern sie." Sirius repeated, pinching the bridge of his nose.
"Speak English, Black." This sentence caused giggles to explode through Remus, James and Peter. "Why is he speaking German?" the Professor asked the three happy students, arms folding.
"There was a rather, ah, unfortunate incident when Remus was studying German yesterday." James replied, cheeks taut from attempts not to laugh again. Really, none of them wanted to increase the ire of the teacher, but Sirius's situation and her shocked expression were all too much.
"Potter, you have five seconds to tell me exactly what happened before I assign all four of you a detention."
James sobered up a little at this, not that he hadn't had a thousand detentions before. "A spell ended up being cast, and Sirius really can't help it. He'll be okay after dinner tonight."
"And pray, who cast such a foolish, childish spell?" Professor McGonagall asked, her face drawn into a hawk like expression. Before James could respond, Remus sighed and admitted,
"I did, Professor."
If Professor McGonagall had looked surprised before, she was positively reeling with shock now. Remus? Casting such an idiotic spell?"
"Detention, Lupin – I must say, I am astonished that you would do this without some prompting from someone else, but clearly not."
Remus nodded, blushing, but still unable to wipe the grin from his face.
Remus wasn't actually there to witness Sirius regaining his powers of speech.
"Hey, Sirius, can you speak yet?" James had asked as evening approached night and they had began to get ready for bed, no longer planning on waiting up for poor Remus.
"No, of course not." Sirius replied, his voice hoarse and cracked from not speaking all day. There was a moment of silence before Sirius's words sank in. When they did, he leapt in the air, whooping and cheering. "I can speak! Fuck! Spatula! Tomato! Cheesegrater! Arithmancy!"
James, Peter and Frank stared at Sirius, who had began to dance around the room half-naked (he had been getting into his pyjamas – thankfully, it was the top half that was bare) and shout random English words, a smile on his face.
"Do you still remember German?" Frank asked, with interest. Sirius thought for a second, still shouting out random words, before responding with a grin,
"Yes! Now, where the bloody hell is that book – I'm going to give Remus a taste of his own medicine!"
24 hours later, when Remus could remember German perfectly but had also suffered a full day of being unable to speak English, he wasn't sure whether to thank Sirius or not.