Imagine:
Set during 'Frightingale'.
Marinette dresses up in the Ladybug outfit (sans mask), all the events leading up to the tension-filled moment, right before both Marinette and Adrien hold the masks in their hands, before Clara gets akumatized, are the same.
Except, that's not Adrien.
It's Felix
Adrien is terrified to out himself like that, so he panics in the room, doesn't even get called out. Why? Clara got ahold of Felix (who suddenly flew to Paris for a 'surprise' visit), dressed up as Adrien, thinking he is Adrien and gives him another Chat Noir suit.
Felix, thinking he can cause mischief, obliges, commenting how distasteful the suit is and what he would change about it...etc.
Cue Marinette and 'Adrien' all nervous etc. Felix tries to over exaggerate, he jokes too hard, puns too hard, flexes a little too much, even flirts but the crowd buys it, hell, even Marinette buys it.
'Wow, these people are blind.' Felix thinks.
Slowly, it kinda gets fun for him so he continues the charade. Until they have to don the masks.
He didn't think this through, why was the girl in front of him looking so nervous for? Were the masks cursed? She looked ready to flee.
Felix, trying to keep the suspense, tries goading Marinette to try on the mask, commenting how she'd 'make a purrfect Ladybug'.
Cue Marinette having an identity reveal crisis
"Wait, what?! Chat Noir?! No, but it can't be-! But he's so convincing!"
Frightingale attacks, the crowd begins to disperse and running away screaming and panicking
Before Marinette could react to transform somewhere, two hands grab her.
One belongs to 'Adrien'
And the other to...
Chat Noir?
A fully transformed Chat Noir stands beside her, fully alert. "Marinette, quick you have to hide!"
"C-Chat Noir?!" she's floored but then laughs at herself.
Of course Adrien wasn't Chat Noir, what was she thinking?
While Chat Noir makes sure Marinette gets outside safely, he turns quickly towards 'Adrien' with narrowed eyes. "Um, Adrien Agreste, right? I think I saw some blond boy around here, looks like you, your brother? Cousin? Well anyway, he's looking for you and really worried, go wait in the park near the Francois Dupont high school, I sent him there!" before he leaves
Felix mumbles under his breath, saying how he's not understanding all the hype around these heroes.
He was sure he would make an even better Chat Noir
Even that Marinette girl bought it
Felix tries not to think about where she might have went, he goes to the park Chat Noir told him about.
Cue Ladynoir defeating the akuma...etc.
Chat Noir doesn't fist bump LB bc he's too worried over where Marinette went. LB detrasnforms, Chat Noir finds her just where he left Marinette to hide. He takes her back to school.
She thanks him and he comments how 'You really looked like the real thing out there, you know? I bet you'd make an awesome Ladybug, princess.' before he rushes away to transform back, leaving a mildly blushing Marinette behind.
Felix observes their interaction, finds her blush interesting, thinking she got a crush on a superhero (secretly wishes he could've donned the mask and pretended to be Adrien longer to cause more chaos)
Adrien confronts him about the suit, replacing him on stage...etc. Felix apologizes, says how he wanted to surprise him and how he missed him, had no idea what was going on so he just played along like the good old times.
The next time Felix visits, he sets his sights on Marinette, trying to drop too obvious hints about him being Chat Noir.
Adrien notices, finds it very weird and there's this oddly tense and charged atmosphere whenever Chat Noir and Felix are in the same room (alone).
CN has his hackles raised and is highkey suspicious over Felix.
Felix challenges him and tries to bet who could make the baker girl fall for them faster as a game.
Chat is super pissed. "Hey, this is not a game! I dont know who you are or why you're doing this but stay away from Marinette!"
Felix, wearing the devil's smirk. "Or what? Is the kitty going to show me his claws? What's it to you if I pursue her, hmm? It's not like a superhero could be in love with a civilian, can he?"
Chat tries not to reveal anything and moves to leave. "Whatever you do, it better not hurt Marinette in any way! Or next time, I won't be so nice."
Felix smiles.
Slowly, he takes out his phone and calls someone.
When the voice on the other line answered, Felix smiled.
"Everything according to plan, I trust you have what I want?"
"Yes. I trust you've kept your part of the deal?"
"Of course. I've managed to gain some very interesting information about Chat Noir, but I'll need some time to deliver you a full report."
"Excellent. You've proven useful, after all. Consider your services done as soon as you give me your findings and in exchange, you'll be compensated for your troubles."
"That's what I hope for. It's nice doing business with you, Hawkmoth."
