lucky accident (гет)

“You really don’t know Chat Noir’s identity?” Adrien asked. “You don’t even have a suspicion?”
“We agreed we’d keep it a secret. No one’s supposed to know.”
“Oh, right,” he said, nodding seriously. “How’s that working out so far?” He grinned at her. Tikki, perched on his shoulder, made a high-pitched sound of agreement.
Marinette groaned. “That was an accident. You weren’t supposed to know either.”
“But you don’t regret me knowing, do you?”
Marinette made a face at him, and he made one back. She laughed and stretched. “No, you dork. I don’t regret it.”
OR: Marinette accidentally revealed her identity to Adrien, but he hasn't revealed his because he fears her reaction.