This is based on one of Yuumi's pictures on tumblr. The basic idea is an undercover Adrien bumps into a prettily dressed Marinette, and she thinks he is civilian Chat. (Also, for the sake of this story, we're going to pretend that Master Fu is still the guardian.)

Caught in the Chat

She had to hurry, had to hurry, had to—

"Marinette, look out!"

Too late. Her foot connected with something, slipped, and then everything in her stomach jumped for her throat and she was falling backwards. There was no time to pull some slapdash ninja stunt. (Even if she tried, the kitten heels she had chosen to wear and the pain throbbing through her ankle would not let it end well.)

This was going to hurt.

Hands latched onto her from behind, stopping her descent with breath-snatching abruptness. "Got you," her saviour said.

She blinked up at him. Not that she could make out much of his face. His hood was pulled down low, messy strands of blond peeping out. Dark sunglasses hid his eyes and most of the upper part of his features, but there was something about his jaw and the grin curving his lips … something that whispered of flirty hand kisses and moonlit conversations, especially since he was wearing all black.

"Chat Noir?" she blurted.

His grip tightened and he stiffened like he'd been hit with one of Lady Wifi's pause attacks. "Wh-what? No, I'm—"

"It is you!"

She clamped her hands over her mouth. Idiot. The smart thing would have been to go along with whatever lie he threw at her. Spare them both. Certainly spare him. Panic radiated through every inch of him, charged like electricity and burning conviction into her bones. This guy was definitely Chat Noir. He had might as well be wearing a nametag on his forehead.

"Sorry," she said. "I just … I didn't expect this. Here. No mask. You."

His expression, or what she could make of it, got tenser.

"But it's okay," she added hastily. "I mean I won't tell anyone, and it's not like I know your name or can even really see your face. Your identity is still safe."

He tilted his head, staring down at her for a moment before a grin got slapped over all trace of tension. "Guess you found me, princess."

She pursed her lips. Even after four years, he still found it amusing to call her that ridiculous nickname. (Though she had to admit it was hard not to smile.) "Maybe you should reconsider your wardrobe choice then."

"I'll have you know black is very in vogue at the moment."

"Uh huh. It also screams Chat Noir."

A soft laugh was tugged out of him and he helped her to stand upright. She bit back a wince. Her ankle was not happy with this new position.

"Would you believe me if I said this was meant to be a disguise so no one would recognise me?" he asked.

She looked him up and down, her nose wrinkling. "The banana suit would have been better."

Another laugh. "I was aiming for something more lowkey. You know, the kind of outfit that isn't going to draw attention when I walk down the street."

"You expecting lots of attention?"

Her tone was teasing, though she couldn't deny that Chat Noir was the kind of guy who would get a second glance regardless of what he was wearing. There was just something about him. Maybe it was his height, maybe the undeniable good looks that even the hood and glasses couldn't hide, or maybe the fact that his jacket alone appeared to cost more than half her wardrobe combined.

"Perhaps," was all he said, and then nodded at her foot. "How's that, by the way? No damage?"

"It hurts a little, but I'll be fine."

His brow furrowed. "Show me."

"Huh?"

He made the motion of walking with his fingers—his bare fingers, and wasn't it odd to not see claws. "Let me see if you can walk."

She let out an exaggerated sigh, just to emphasise how much of a worrywart he was being, and took one step onto her injured foot. Pain shot through her ankle in fresh, hammering ripples. Awful, awful ripples. She sucked in a sharp breath.

"Knew it," he said.

"You don't have to sound so satisfied."

He threw his hand dramatically over his heart. "I would never take satisfaction in your pain."

"Yeah, yeah, you're a real gentleman."

"You mean gentlecat?"

She spared him a fond eyeroll but was otherwise too busy fretting over what she was supposed to do now to respond. Transforming into Ladybug was out of the question. Tikki had been feeling a bit under the weather and was in Master Fu's care.

He held out his arms. "May I?"

She blinked.

"I don't think you should be walking on that foot," he explained. "And hobbling on one heel doesn't sound fun."

Her lips curved. "You know all about walking in heels, huh?"

"You'd be surprised."

She bit the inside of her cheek so she wouldn't laugh. Her civilian self wasn't supposed to know about the Reflekta incident or how he'd mastered walking in platform heels. "I'll take your word for it."

After being granted permission, he lifted her up so he was carrying her bridal style, careful not to jostle her foot. A light blend of citrus and musk teased her senses. Clean, fresh, and unbelievably good. She had to resist the urge to bury her face into his neck and sniff. (Because that would be weird.) More distracting was the sensation of his bare hand on her thigh. There was nothing inappropriate about the way he held her, but the warmth of his touch still sent little tingles through her from the point of contact.

Ugh. Get a grip. It was just Chat. Just a maskless, very-much-civilian Chat whose face was now inches from hers. Those glasses looked awful flimsy from this close …

"You good?" he asked.

A small nod was all she managed. (Ugh. Why was she getting shy all of a sudden? Even her cheeks were too hot.)

He carried her towards the bench farther down the street.

"So, you got a date or something?" he asked, and though she couldn't see his eyebrows behind the sunglass frames, she was sure he wiggled them at her.

A few creases formed on her brow. "Why would you think that?"

"Oh, sorry, I just assumed with the dress and hair and, um … I'm gonna be quiet now."

A laugh bubbled free of her lips. He looked so awkward, poor thing. But it was an understandable assumption. She didn't often wear her hair in a bun, and her dress was a cute, red cocktail one that showed off a lot more leg than usual. Combined with the black heels and makeup, it was no surprise she gave off the dressed to impress vibe.

"No date," she said, settling her arms more comfortably around him. "My friends and I are having a girls' night out. Dessert, karaoke, dancing—all the fun stuff." Her lips formed a pout. "Though I probably won't be doing any dancing now. Knew I shouldn't have risked the heels."

"To be fair, I don't think it was the heels' fault you tripped on that bottle."

Her bottom lip jutted more. "Are you making fun of me for being clumsy?"

"I would never."

"Somehow, I don't trust your word at all."

"Meowch. And here I am trying to be a good gentlecat to you."

She hid her smile against his shoulder. No need to stroke his ego by letting him know she found him funny. The fact she could smell his cologne better in this position was just a happy bonus. He smelt so amazing. In fact, it was a lot like …

"What cologne are you wearing?" she blurted, raising her head to look at him.

"Uhh." His nose wrinkled in a far too cute way. "The latest in the Adrien range."

"I knew it! That's why you smell so good!"

His lips twitched. "Oh?"

"I, uh …" Heat bloomed on her cheeks. "It just seemed really familiar and, um, Adrien is my friend so I, um, have smelt it on him before. N-not that I go around sniffing him or anything." A strained laugh, followed by an equally strained smile. "That would be crazy."

"I'm sure he'd be flattered you like his cologne."

He was totally laughing at her. She could hear it in his voice. No doubt his eyes would be twinkling as well if she could see them.

Ugh, ugh, ugh. This was mortifying.

"I'm not talking to you anymore," she grumbled, and burrowed her face back into his collar.

He did laugh that time. "Come on, Marinette, I didn't mean it like that."

"Nope, not talking. I shall hide in my shame right here."

"It's really not that bad."

She shook her head.

"If it helps, I think it's sweet you remembered your friend's cologne. Plus, I'm flattered you like it."

They reached the bench. She met his gaze, or at least as much as she was able to through his dark sunglasses. His grin was the kind that could ruffle and smooth even the most guarded of hearts—far too charming, but in an entirely unassuming way. (Curse her kitty for being a genuine sweetheart under all his silly antics.) Worse, it was getting harder not to be hyperaware of the points of contact between them—his hand on her bare skin, the other supporting her back. The toned muscle she could feel through his clothes.

Fluttery wings stirred in her stomach. Her cheeks grew frustratingly hot.

"Marinette?" he prompted, tilting his head.

"Just put me down," she muttered, looking the other way.

Of course he took great care in how he sat her on the bench. Then he knelt in front of her and was about to pick up her injured foot, only to pause.

"With your permission?" he asked.

Face still flushed, she nodded.

He gently removed her heel and examined her ankle and the surrounding, swollen area. His touch was careful but confident. No smile could be seen on him now. He was all concentration. All dedicated to helping her.

She cursed her treacherous heart for daring to beat faster.

"It looks like a sprain," he observed.

A groan escaped her. "You're kidding."

"Afraid not, but can't be certain until you see a doctor." He placed her foot down and stood up, handing her the heel. "Come on, I'll take you to the hospital."

"But Alya and—"

"No buts. Your friends will understand."

He scooped her up before she could protest any further, flashing her a cheeky grin. Fresh heat bloomed on her cheeks.

"You aren't seriously planning to carry me all the way to the hospital, are you?" she demanded.

"Course not." He headed away from the bench. "I'm gonna transform."

"What? But y-you can't! There's all these people and—"

"Don't worry, I know what I'm doing."

"Chat!"

He laughed and ducked into an alley with her, finding a spot that was hidden from prying eyes. "See, no one will know."

She pulled her most unimpressed face. "Except I'm right here."

"Yeah, but I trust you."

Her heart fluttered. Oh.

"Though I am going to have to ask you to close your eyes."

She did as he asked, trying not to dwell on how the blanket of darkness only made her more aware of his arms around her. So warm, so secure. The drumbeat in her chest got faster and faster.

"Plagg," he whispered, "transform me."

The magic swept over them both in a rush, flaring in a bright burst behind her closed eyelids.

"Marinette."

She opened her eyes and looked into vivid green. There was the familiar mask, the cat ears.

"Let's get you to the hospital, shall we?" he said with a smile.

"Grounds sate." Her eyes bulged in surprise. "I-I mean sounds great."

Oh no. Oh no, oh no, oh no. Not again.