It's only after you put the groundwork in that you can delegate.

Sadly.

More fortunately, talking to the sixth and then seventh years goes well. They find a handful of students doing both Defense and History at the NEWT level - most of them are hesitant about shouldering the entire risk, though they're willing to help 'tutor' and to bring some questions to Lupin, but one seventh year is eager to help, and he knows two people in other Houses who should help as well. 

They can also get a scattering of ideas from the people they trust with telling about the Come and Go Room - testing if you can ask for a room that'll keep people out is the big one, and if that works at all what the limits are on it. A room that requires a password to enter. A room only specific people can access. 

One sixth year in Charms with them also suggests using magic - like the Protean Charm - to communicate room changes. It isn't the most secure method, since a charmed object can be stolen, but it's more efficient and can be better used to warn people than word of mouth. 

If someone wants to make a project of Protean-Charmed items, they're welcome to do so. For the other ideas, the only way they have to check the rules of the room is experimentally, so they'd best start work.

They can delegate protean charms stuff to the person who suggested it, bring a few of the more scientifically minded Ravenclaws in for experiments. Get people to document their results, too. 

Yeah, it'll be no good if they can't actually remember any of the rules they find.

Or if someone's doing something weird and doesn't explain it well enough. 

Right. At least this way they have something to slap their faces with until they make more sense.

She giggles. 

And the experiments and preparations can begin - you can exclude specific people, which none of the testers can get around. You can exclude types of people, including by weird things like favorite sports team, but that's significantly easier to fool - they think Occlumency might actually get around the exclusions, and it's possible that none of them are good enough Occlumens to convince the room they're actually someone else. Still, the snitch squad aren't exactly masters of the craft.

You can also set a room so it can only be accessed by specific people, but some tests with hiding items in those rooms reveals that you can retrieve any items left inside the room from a different room (there's a specific room-version they discover that collects every item left in the room, which will get even items hidden in a room-version meant specifically to hide them, which usually prevents you from getting a room-version with everything a certain person has ever left in any room-version).

Relatedly, you can name a room-version, tell someone else the name, and they can ask for that room and get the same room you created even without knowing what it is or looks like. You can overwrite room names, though some very stubborn experimentation reveals the room keeps a memory of past room versions, and you can access the overwritten ones still. 

You can set a password on the doors at the end of the escape corridors, and you can set it to exclude people, but they can't figure out how to get the escape doors to have the same properties as the main door. They can't figure out how to make a door in the room that goes to variable places, either, but they can get some pretty blatant space warping if they set destinations ahead of time - full corridors out aren't actually necessary for exits. 

One muggleborn who likes spy movies figures out you can have multiple doors on an escape corridor with different opening conditions, and the same door can have different opening conditions coming and going, so they could make the room with a corridor which has a password door where it meets the castle proper and a door that only opens from the inside where it meets the study room, and a one-way window in that door for the study room to look into the corridor, but it'll let people leave freely - and another test shows you can have it let specific people leave freely and require passwords for everyone else. 

You can't modify room-versions while someone's in them unless you specify how it can be modified ahead of time. 

Fortunately, at that point they're able to offload the project onto someone else - with a few suggestions, including for 'maybe don't get too carried away' - and then refocus on their own projects. (Anathema does make sure she knows approximately when History meetings are happening, even if the two of them usually don't attend - the Come and Go Room sounds really excellent for their personal projects, since they can get any restricted book they want, a wide secret area for Ellie to practice flying in... Probably a fire-proof area, too. And a good place to practice Defense - maybe they should tell Fay, even, so she has a place to practice her more dangerous spells...)

Yeah, this room is handy in a myriad of ways. Pity they didn't learn about it earlier.

Yeah! They could've gotten a lot of use out of it.

Oh well. They still have two and a half years to make the best of it.

She nods. The book retrieval's probably going to be her favorite - she wonders what its limits are...

Probably nothing that isn't in Hogwarts's library. Maybe everything that's ever been in it, though that's a stretch.

Yeah, sadly...

Potentially testable, though, if they get some muggle books.

It'll probably also fetch any books that've ever been left in it, though that relies on a lot of luck with past people having found it and left books behind...

There's been enough of them over the years, judging by the state of the lost and found.

Might not be all interesting, but, yeah, there's probably a good number.

If they get bored in the near future they can investigate.

Small chance of that, then.

Maybe next year.

Probably by the time they ever get bored, Hogwarts will be long behind them.

The perfect time to come back for a couple years as Professors.

Maybe once Dumbledore isn't Headmaster.