Anon prompted: "We all know that Erik speaks a lot of languages (as shown in X-Men FC), and I bet he falls to using different languages when he curses or mocks people and so on; what if he also confessed his feelings to Charles in German or French or something, not knowing that Charles actually spoke that specific language as well. (Alternatively, this could be Spideypool or Tony/Clint if you'd prefer. I really don't mind the couple.)" So yeah, considering this is set before google existed, Charles and the X-Men can't just look up what Erik's saying. Second half of the story is way better then the first half, I'll have to come back and edit it later.

Charles first noticed it while Erik was 'helping' Sean train.
Sean was…not having a good day. It was after his fifth or six failure that it happened.
Erik swore.
In German.
Sean, without needing a translation, sulked.
Charles felt a small flush cross his face.

After that, it happened more frequently, or perhaps Charles hadn't noticed before, but Erik used German all the times. To criticise Angel when she'd stole the last of the cornflakes, express annoyance at Havok and Mystique's banter, apologise to Beast after an argument.
Charles was beginning to realise he had a thing for German.

It took a few months for Erik to turn that German charm on Charles.
Well.
Charm may have been a bit of a strong word.
They were arguing. Erik believed Charles was too lenient on Banshee. Charles believed people should be able to walk away from a training session in one piece.
"Banshee is still a person!"
"He is a mutant." Erik retorted. "Humans will not let his 'personability' get in the way of shooting him."
"Who said anything about shooting anyone?!"
"The world is a darker place then you know, Mein Schatz."
My dear.
The conversation stopped, both of them breathing heavily after so much yelling.
Erik looked…embarrassed.
"I think I know enough." Charles said.
Erik nodded, but the anger was gone. "Whatever you want. It's Sean who will suffer."
Then he strode away.
Charles frowned to himself. It wasn't usually that easy to persuade Erik to do anything.

Erik shyed away from him the next few weeks, away from everyone. When cornered he only answered in short sentences, never more than three words at a time.
Raven accused Charles of crushing his rebellious spirit. Banshee and Havok teased him about it.
Finally Charles had had enough of Erik leaving the room everytime Charles entered it.
"Erik!" Charles called, cornering him in a hallway.
Erik hesitated. "Charles." His eyes darted around.
"I wanted to…apologise."
Erik blinked twice at him. "I beg your pardon?"
Charles waved his hand awkwardly. "For..um.. upsetting you."
He still wasn't sure what it was he'd done. He'd played the conversation over and over in his head, even showed it to Raven and Hank via telepathy (minus the Mein Schatz, of course, that was something he figured should be edited out), to no avail.
Charles figured that apologising was the best way to go. He'd obviously done something wrong, or upset Erik in some way, and even if he hadn't, he figured Erik would appreciate the gesture.
"You…you didn't…" Erik blinked at him. "Thank you."
Charles nodded once, and walked away.

Things went back to normal after that. Erik turned up, criticised everyone, and sulked in the library.
Charles and Erik went back to fighting every other day.
With one addition.
Erik had started throwing in German endearments. Schatz, Liebchen, Schöner. Always when they were fighting. Only when they were fighting.
Tossed in at the end of sentences, spat at him as insults.
It was incredibly confusing.
Charles had tossed around the idea that Erik didn't really know German as well as he claimed, but he had seen inside Erik's head, and knew that couldn't be true. Besides, he still continued to insult the rest of the group with ease.
In the end, Charles chalked it up to some type of ultimate sarcasm, some dry wit that Charles couldn't understand. Something cultural perhaps.
This carried on for a few months.

Charles folded his arms. It was nearly midnight, and Charles had had to corner Erik once again, this time in the library. Erik was really trying his patience.
"Just admit you were wrong, Erik."
"I was not."
"You almost got Angel killed."
"That's not my fault."
"Oh, I suppose it's mine?"
Erik moved closer to him. "If you'd implemented the training I'd suggested-"
"Then all of them might not have even made it to the point where you could use them for your own gain."
"For the gain of mutantkind," Erik corrected.
"Don't pin this as a humanitarian exercise, Erik, you know what this was."
"Oh I know." Erik said and paused. "Ich Liebe Dich," He hissed, and began walking away.
I love you.
"Oh." Charles' eyes widened, taken out of his anger by surprise. "I didn't… I didn't realise."
Erik stilled. After a pause, he turned his head toward Charles. "You can speak German." It wasn't a question.
Charles blinked at him. "Of course I ca…Why would you… I…oh." He fell silent. Erik didn't know he could speak German.
Erik had just confessed and he hadn't known Charles could understand him.
Erik was walking forward, striding away from him on his impossibly long legs.
"Wait!" Charles called, jogging to catch up to him. He pulled on Erik's arm. "We need to talk about this."
"Hardly." Erik was grinding his teeth together.
Charles was nodding to himself, trying to get his brain to work. "No, no I think we do."
Erik turned to look down at him, defiant. "What would you like to say?"
"J-just let me think." Charles didn't let go of Erik's arm as he dropped his head and closed his eyes.
Erik shifted, and Charles knew he was holding back from fidgeting.
"You said you loved me," Charles started in a small voice.
There was a beat.
"I did."
"You've been saying other things too, these past few months."
Erik nodded curtly.
"I thought… I thought you were being sarcastic." He flushed.
Erik didn't say anything.
Charles pulled a face. "This is supposed to be a discussion."
"What do you want me to say?"
"Well, I suppose you could ask me out."
Erik's nostrils flared and he pulled his arm free and strode ahead.
"I'm not joking," Charles said, having not moved.
Erik halted. "You are."
"I'm not. If you'd asked me out earlier I would've said yes too."
"I…"
Charles cleared his throat. "Not that I don't mind your particular style of flirting."
Erik looked at him. "Would you?"
"Would I what?" Charles replied in mock innocence, a grin blooming on his face.
Erik glared and closed the gap between them, sticking a curled finger under Charles' chin to force him to look him in the eyes. Charles' grin widened. "Would you go out with me?"
"I go out with you all the time," Charles commented. "Just last week-"
"On. A. Date."
"Hmm," Charles pulled his head free, and pretended to consider.
Erik's glare deepened.
They were playing with each other now.
"Well, since you put it so nicely…I am free tomorrow night."
Erik sighed softly and Charles turned his grin back on him.
"I suppose I could work with that schedule," Erik told him.
Charles fluttered his eyelids in another act of mock innocence. "Well, I think I have another slot in a fortnight."
"Tomorrow will be fine."
Charles nodded. "If you're sure."
They fell silent, ignoring the fact that they were incredibly close, and Erik's hand was still on his neck.
Charles hummed and opened his mouth, but Erik beat him to it.
"Darf ich dich küssen?"
May I kiss you?

So um yay! German! Um~ so I basically started teaching myself German for a few months last year, before uni started back up, so like... I decided to use what I know, instead of doing long google translated paragraphs...um yeah. Also I tried to be more uh elegant in my writing. Did it work? Like I was going for flowery and everything, idk.