She lets him open the Room however he wants.

As much as she, or rather, the Harry part of her, really wanted to screw up whatever Draco was trying to do (Interfering with Draco was just an instinct after all these years at school together), the more rational, more Bathilda part of her knew that was an awful idea. If the plan was to figure out what the **** Eaters were doing, and Draco was somehow involved in that, then messing with his use of the Room would just make him suspicious, completely counter to her goal.

So, completely counter to everything she really wanted to do, Bathilda didn’t try to alter how the Room would appear at all, and did a good job of looking surprised when suddenly a room existed in the corridor. As Draco approached the door, looking smug, Bathilda muttered, “I guess Hogwarts does have some interesting things in it after all.” After all, she was playing someone who’d never been to the castle until this day. “So, what is this place?”

When they entered the Room, she found it in a way she’d never seen before: an enormous storage room, with tables absolutely covered in random things. They made their way through the aisles, Malfoy clearly knowing where to go the entire way. Finally, he answered her question. “I’ve no idea what the name is, but I found it last year.” Apparently, that was all he had to say to her, at least at that moment. So, Bathilda just followed him, her curiosity growing with each step. Finally, they steep in front of something that looked vaguely familiar to her. “It’s still hear...” she heard Draco mutter, before turning to look at her in an attempt at menace. “First things first: if you tell anyone about anything I show you, anyone at all, your first year at Hogwarts will be your last. Understood?”

Knowing everything she did about Malfoy, Bathilda knew the threat was, more than anything, a bluff. Still, the more Slytherin parts of her did shiver a little at the threat, something new to someone used to being a Gryffindor. Either way, she nodded, looking annoyed. “Yes, yes, I won’t tell anyone. You can stop with the threats, blondie. Now, what’s this dresser have to do with anything?”

While she couldn’t exactly place how, Bathilda could see that Draco was looking at her differently now. The only thing she could tell for sure was that the hostility had ebbed away, though his smugness was still there. “I’ve been given a mission, from the Dark Lord.” That froze Bathilda immediately. She hadn’t guessed Malfoy would be so direct about this, or that he would even be given any such task by Volde-...no, by You-Know-Who. (Bathilda wasn’t sure why, but she found it hard to think of that name now.) “If I even think you’ve told anyone, or will, you’ll be under my Imperius Curse before you know it.” Annoyed, Bathilda just rolled her hand at him. After all, she’d already agreed not to tell. Looking even more comfortable with her now, Draco asked, “Do you know anything about fixing Vanishing Cabinets?”