Marinette is the main female protagonist in Miraculous Ladybug. She's a young girl with a kind heart and a secret identity as a superhero. As for Camemburt, it's likely a character made up for this particular fanfic idea. Maybe the author wanted to create a new love interest for Marinette, so they came up with Camemburt. But again, this is just speculation without actually reading the story.
Marinette could use her wits. If she's tied up, she might be able to find a sharp object nearby to cut the ropes. For example, if she's in a room with some old furniture, there could be a nail or a broken piece of wood that she can use.
Another reaction could be that Marinette pretends to cooperate with Adrien at first. By doing this, she can buy time and look for an opportunity to escape or get help. She might act as if she is okay with what is happening while secretly planning her next move, like leaving a clue for someone to find her or finding a way to disable Adrien temporarily.
I don't have a clear idea about that. It might have elements of adventure, determination, and maybe a bit of luck. But to know for sure, you'd need to explore reliable sources dedicated to this story.