"I don't think El would go through a door I did this spell to."

"Reasonable of her."

"I think El would go through a door I did this spell to after I told her I'd already done it and been fine but, also, she'd probably chew me out for doing a weird spell that I didn't know exactly what it did the first time. Which would also be reasonable of her." 

"—oh but the door opens to the inside of our rooms. My room? My room at least."

"Well, yeah, but we have the spell, we can cast it again later."

"I don't, I gave it back to the void. I also, uh, am not sure I believe the spell actually did anything or matters. This place does not fit with our understanding of how magic works and I got here even though I specifically did not cast the spell."

"...Well, Orion and I have the spell, we can give it to you that way. I suppose you're right about the latter part but I have no idea what that really means in practice."

"Hey, uh, person with the napkins—actually we've been so rude, we've been ignoring you, please feel free to participate in our conversations. But I wanted to ask, what happens if one of us walks out and then tries the door again? I assume their door won't be leading here forever, but..."

By and large the door you came through will resume its normal behavior after you let it close on Milliways.

"...ah. And, ah, did that spell they cast actually do anything?" he asks, offering his napkin to the nearest not-Scorpius.

Quite likely! The door usually comes and goes of its own accord but some people can force it; perhaps the spell is a means to do so.

"Oh, okay, that's promising. Is there a way to verify it?"

Other than by trial and error I don't know of one.

"...somewhat less promising." He shares these napkins with the others, too. "So, uh, I never did ask. Who are you, what's your name?"

You can call me Bar. She/her.

"Oh, are you, like... the building?"

No, I'm the bar. If you go knock on the window that won't affect me.

"Don't bars usually do alcohol? I don't think this has alcohol in it." She gestures with her smoothie, which she is giving a slightly dubious look, on account of being less confident of the absence of alcohol than she would like. 

I'm not limited to beverages at all, let alone any specific kind!

"What do you do besides beverages?" 

I can sell most medium sized nonmagical inanimate harmless items.

"...Huh. Define nonmagical, like, spellbooks usually get magic fast but often they don't start out that way?"

If they're widely published I can access them; if they were secret it's unlikely.

"Hm. I know the Golden Sutras used to be fairly widely circulated...but that's actually not really a priority right now because El has them anyway."

"Not everybody is El."