Marlene's expression changed from one of exhausted desperation to one of annoyed irritation as she was hit with the Silencing spell -- clearly it was someone who knew who she was, or else the Death Eater in question wouldn't have bothered with a spell intent to shut up someone who they didn't know to be a loudmouth. Tiny blond fellows. Who was tiny and blond and death eaterly who knew her?
There wasn't time to think about it, though, before the blasting curse sent her skidding across the floor and slamming against the wall, her head smacking against the wall hard enough to cause Marlene to see double. Not quite sure which Barty was the real Barty, she prayed that she'd get lucky enough to hit the real one as she shot a streak of green light slashing toward him as she crawled back behind a sofa, knowing that it was the slug-spewing spell but hoping that even if it DIDN'T hit the Death Eater, the spell's colour would be enough to freak him out.