Marietta couldn't believe that Granger had the nerve to talk to Jayne, trying to undermine her in front of this woman. Not to mention, she had no idea who that actually was - it wasn't even Pandora in control just then. It was a gutsy move for her to try, but it would cost her.
"Oh on the contrary, Jayne," Marietta replied in a sickeningly sweet voice, "she's quite scared, she just thinks that she will somehow be able to use her cleverness to weasel her way out of this. Unfortunately for you, Granger," Marietta said and lowered her wand to point at Hermione's ankle which she twisted easily at the wrong angle, breaking bone, "your pathetic attempts at mind tricks won't be working tonight," she finished with a smile, twisting a finger back the wrong way as well.