"Why's there a Forbidden Forest. What's forbidden about it, has it got evil magic plants? ... Actually of course it obviously does, even the normal world has evil plants, I read once that the Royal Horticultural Society says there's over a hundred thirty different plants native to England that can be poisonous and they must only know about the ones that aren't magic, mustn't they. That is going to be a really interesting class, you're so right." Excited bounce.

"I heard it's forbidden 'cause there's werewolves in it, but I dunno if I believe that. I bet it's got evil plants too."

"You don't know if werewolves are real or you don't know if they live in the Forbidden Forest?"

"Second thing; they're definitely real."

"Huh. They wouldn't stay in the forest, would they, if they lived there? Fantastic Beasts and Where to Find Them says werewolves are one of the only magic creatures that hunts people on purpose and if it is forbidden for people to go there they would have to leave to do that." Considering nail-bite. "Maybe it is also against the rules for them to leave."

"I don't know how you'd stop them from leaving. . . .Is there magic for making it impossible to leave somewhere?"

"Nah. There's magic prisons but they have, you know, walls and stuff."

"Really! And that works, for them to just have walls?" Fascinated chin-finger-tap. "Can you only make walls that can be walked through and not walk through walls? I guess that second thing can't really be a charm, can it, you'd be casting it on yourself and also the wall."

(A Charm, the theory book explains, is formally so defined by its behavior of performing a single specific effect - never several in a row, like a Transfiguration - on either a person or an object, or a reasonably uniform group either thereof, but not a mixed group.)

"I don't see how you could walk through random walls and not fall through the floor, yeah. But imagine if you could, though--d'you think you'd get lost in Hogwarts more or less that way?"

"If nothing else it'd be easier to get un-lost, right, because you could just walk to the edge and look outside."

"Is that a problem a lot, getting lost in Hogwarts? Isn't there a map or anything?"

"Oh, yeah, everyone gets lost loads of times first year. It's too magic to map. I'm not even sure you could just walk to the edge even if you could walk through walls, come to think. If you weren't going down hallways like it expects you to . . . " he shrugs. "Most people have the hang of it by Halloween."

"Too magic to map? What happens if you try to map it anyway?"

"Then your map'll be wrong? All I know is no-one's ever done it even though they could make a fortune selling copies to first-years."

"Huh. Is that what Unplottable means, it says that in Hogwarts, A History but I think it just assumes you've heard the word before."

"I think Unplottable is something for making Muggles not be able to find somewhere but maybe it's related."

Thoughtful nodding. "Maybe the library will have a dictionary."

"Yeah. I'm hoping it has an encyclopedia. It's definitely going to be amazing." 

"Am I going to need to drag you two out of there and make sure you eat?"

That was pretty adjacent in content to rude comments classmates have made before (it is, apparently, embarrassing and uncool to prefer to sit in the library instead of the cafeteria at lunchtime, to be more interested in finishing a book than to run after the ice cream truck, etcetera), but he said it in a remarkably friendly tone. And smiled, even.

Are they ... friends now. How. Why. Did Bruce do this?? If so he is even more her new favorite person???

".........maybe?" she hedges.

Oh good the girl who seems to reliably know what to say said what he was considering saying. He nods. "Maybe."

Ron laughs, with apparently genuine mirth. "As long as you don't turn out like my brother Percy. He thinks he's better than everyone else because he's a prefect and gets the best marks."

This remark causes Bruce to get lost in thought. At Hogwarts nobody is going to be comparing his marks to Dudley's marks and getting angry if they're too much better. Getting the same marks as Dudley won't even be an option.  Given that, what kind of marks should he get? Indifferent is good for avoiding notice, but aiming for good marks might help him learn magic faster. And of course it's possible he'll have to try as hard as he can just to pass; maths and grammar and things are easy but magic is potentially much harder. He'll have to improvise.

But she is better than everyone else because she gets the best grades. That is what grades are for. Right? Dumbledore famously got very good grades and he is obviously the best person to aspire to be.

It is actually really difficult not to say that out loud, but she is not going to! Not when she has been so specifically and helpfully informed that she is not supposed to. Hermione has been presented a shiny new opportunity and she is going to get a good grade in friendship, a thing that is normal to want and possible to achieve.

She grins, a little manically, and instead says, "Guess I'd better prove him wrong by getting better grades than him."

Nailed it.

"Good luck!"

If Hermione wants to get good marks that's probably an argument in favor of aiming for them himself. Unless that was a joke.