Based on agrestenoir's post on tumblr. The gist: Lila tells everyone she's been kissing Chat Noir, Adrien calls her out on it, she asks him how he knows, and he panics and says Chat Noir is dating Marinette. (And Marinette overhears.)

I couldn't resist.

The Fool Who Dug His Own Grave

This is bad. Lila is a liar, but Adrien now knows what it feels like to hold all the truth of the world in his hands while also teetering over the abyss of The Fool Who Dug His Own Grave. Sirens of panic blare through his mind. His heart thumps and sweat slickens his palms. How the heck is he supposed to explain why he knows with a hundred percent certainty that Lila has most definitely not been kissing Chat Noir without exposing the fact that he is Chat Noir?

"Well?" Lila demands.

He swallows. Glances to the left, glances to the right. Catches sight of blue-black pigtails. The sirens get louder in his mind and become a messy clash of words like, IDIOT, SAY SOMETHING! DON'T JUST STAND THERE! SAY SOMETHING!

"Because Chat Noir is dating Marinette."

Lila's jaw drops. Adrien wants to clamp his hands over his mouth. Why had he said that?

He risks a glance to the right. Marinette stares at him with wide eyes, a croissant halfway to her lips. It slips from her fingers and hits the desk. The sound shatters whatever spell has kept Lila frozen. She rounds on Marinette, but the rest of the class are already crowding on Marinette and their voices pile over each other as they demand if it's true. Alya and Nino are especially vocal.

"U-um," Marinette says, leaning back from everyone, "I d-don—"

"It's obviously not true," Lila says, flicking her hair over her shoulder. "You just have to look at her face to see that she lied to Adrien."

Marinette meets Adrien's gaze. He bites his lip, gives her apologetic but pleading eyes.

"It's true," Marinette says firmly. "I'm dating Chat Noir."

oOo

"I am so sorry, Marinette," Adrien says once they're alone. "Thank you for going along with that."

"It's okay." She shuts her locker. "But, uh, why did you say it?"

He sighs and leans against the lockers. "I'm just so sick of Lila's lies, and when she asked me how I knew she was lying, I panicked and—"

"You … panicked?"

His eyes widen. He goes very still, like an animal caught in the headlights. "Um …"

The abyss of The Fool Who Dug His Own Grave looms before him again. He really should have stayed home today. Maybe he should just put sellotape over his mouth.

Her head tilts. He can almost see the cogs working in that clever mind of hers.

"Oh, look at the time," he speed mumbles, glancing at his wrist (where there is no watch). "I've gotta go. Got a photoshoot. Thanks again, Marinette!"

He waves quickly to her and flees, even as he wants to bash his head over and over against wall. He is such an idiot.

So I dunno how long this is going to be yet (because yay impulse writing), but I plan to keep the chapters short, so I should be able to update pretty frequently.

Next up: Marinette gets a visit from Chat Noir. She has questions. Many questions.