"Yeah. Don't some breeder species have to leave new individuals amongst humans?"

"I'm not aware of any that have to, but glowgolds make a habit of it off the top of my head."

"Yeah, so, we're at least similar enough that fairies can easily pass for humans when raised from infancy there. Why do they do that anyway?"

"I don't know, I'm not a glowgold."

"Fair enough."

More gate tests?

More gate tests.

They can probably spend a few hours on this.

Yup!

Eventually Mortal will suggest that they return to HQ since Yellow should be returning soon and she wants to check on her mother and it's close to time to sleep according to the schedule they've been keeping.

No objections.

So she reopens one of the gates that are large enough for people to go through from there to HQ which she made while doing gate science, steps through, and deactivates the security system.

Yellow is back in a timely manner.

And Mortal checks up on her mother who is still decompressing back at their original place, and before they retire to bed Mortal picks Promise's brains on whether to deactivate the security systems in the various safe houses.

"They seem a little elaborate and no one actually tripped them, but what's the advantage of taking them down now they're already up?"

"Not having to deactivate them whenever we go through gates, though that's just a word for me and a palmprint for you."

"It's not that big a deal."

"I suppose it's not. Not hard to deactivate and reactivate, either way," she shrugs.

"And that little bit safer."

"Yeah, I guess. I'm going to bed, then."

"Sleep well."

The following day, she asks Yellow to go back to the library to get some books on sorcery, if he pleases.

Yellow wants to know how long they're planning to keep him.

As far as Mortal's concerned, until Thorn's court has been completely neutralised, i.e. Thorn & co. are sparrows, but if Promise disagrees they might as well release him now and one of them could go instead.

Eh, that's okay with Yellow, he just wanted to know.

He flies off to the library.

And they can resume doing various science and when they don't have immediate science to do that wouldn't just be a repeat of answers contained by books Mortal works on some project on her computer.