"Oh I see. It's good to know the limitations, then," he responded with a quirk of a smile, his hands slipping into his pockets as he walked beside her. It was a nice day out, at least, although he still felt a little jittery and unsettled. It had been a while since he managed to get his hands on a cigarette, and he couldn't help but hear Remus and James' voice in his head scolding him for picking them up in the first place. He never thought he would actually miss being chastised by his friends. He pushed the thought away again.
"Everybody is useless here until they're needed," he reasoned aloud, shrugging. "I was useless until you needed a swim, and I was useless until you needed blueberries. After I show you where I got them I'll be useless again, but you'll always be needed around here. Believe me, in places like this, people get hurt." He muttered the last part under his breath, his attention turning to the large wall before looking back at the gaping doorway up ahead of them. "How what, do you make flour? ...You guys don't learn that in school?" He looked surprised when he glanced back at her, cocking an eyebrow. "...Well... no, I guess you wouldn't, would you?" It wasn't like Muggles had potions class. "You try to harvest the seeds or oats from them and you grind them down into a fine powder, it'll make a good flour or flour substitute when it's needed. It's a really simple process, we learned it first year."
He gave a facial shrug when she said that she was invisible, and although he was smart enough to catch himself he almost told her that she was lucky. He'd be in a much better place right now if no one gave a shit about paying attention to him. "I wish they didn't notice me, either," he admitted aloud finally, giving an annoyed sigh out through his nose. His smile returned, however, when she threw his own question back at him, and he turned his head to look at her once again. "Oh yeah. I mean, it' complicated stuff, time travel, the easiest way is to get your hands on a time turner but those are bloody rare, and they're damn expensive. There are some spells and potions that can do it but it's dangerous, we're talking high level magic there, but-" he stopped suddenly, as if just remembering that he was talking to someone who probably had no idea what he was saying.
"Sorry," he began apologetically. "I've never really had to explain something like this before. Where I'm from we're not allowed to speak of it to people who don't know about it, it's against the law." He hesitated. "The Ministry doesn't think that mu- non magical folks are ready to know about us, just yet. I'm conflicted about that, I feel like they have a point but I also feel like if we did it quickly, like tearing off a bandage, it would be easier. But yeah. Magic." He finished flatly, deciding to start off with that.