"Oh, and I have a letter from the archmage for someone here--I can't read this language, I'm using truespeech--it might be for you?" She fishes the letter out of the bag of holding and shows the address.

"Ah, yes, that would be for me." The letter floats gently out of her hand and opens itself on the way to his. 

Hello, Albus! I've sent Samora to help with your Voldemort problem. Let her hang around Hogwarts and make sure she has plenty of opportunities to go looking for trouble. Actually tell her the things she needs to know, if you can bear it. And be glad you're not one of the Evil yous, the Evil yous don't get such nice presents.

[Dumbledore's time travel password redacted for privacy]

[Archmage proof-of-work block redacted for being in inscrutable spell diagram notation]

Toodles,

Nefreti Clepati

P.S. Try not to eat so much of the anomaly's brain.

One of Dumbledore's eyebrows climbs gradually into his hair. He incinerates the letter with a twitch of his wand; within seconds not even ashes remain of it.

If she's cleared for any of that, she'll get told it eventually. Or maybe none of it has anything to do with her, maybe this is just how archmages on different planets send each other mail, what does she know.

The Weasleys (and Potter) have unhugged enough to be conversational.

Dumbledore turns a twinkling eye on Harry. "I'm glad you three all made it back safely. How did you find the Chamber of Secrets?"

Harry explains the book page he and Ron found in Hermione's petrified hand with the note "pipes", the realization that a basilisk in the plumbing explained why Moaning Myrtle died in a bathroom, their decision to tell Lockhart and discovery of Samora along the way, the confrontation with Lockhart--

"Oh no, he's probably still there, isn't he".

"It seems likely." He scans the group for people who could reasonably be split off from it, decides against sending Samora to navigate Hogwarts unassisted, and looks at McGonagall.

McGonagall steps out for about two moments*, then returns. "He's being dealt with."

(She sent a Patronus to Snape. She's not leaving this conversation until she finds out what happened to her students.)

*A Golarion time unit based on the length of time many spells take to cast. 

Harry, on being prompted to continue, explains their journey through the Chamber and their discovery of Riddle and Ginny. Then he hesitates, trying to figure out how to explain the whole diary possession thing in a way that makes it clear that Ginny didn't do anything wrong and how to prove what he says.

"What I would quite like to know is how Voldemort managed to enchant miss Weasley, when according to my sources he's hiding in the forests of Albania."

Oh, maybe that's why she hasn't vanished back to Otari yet. "Cursed diary possessing miss Weasley. Some kind of enchantment-necromancy combo, if I had to guess, but I don't because we can just show you. Harry, you've still got it, right?" Obviously an archmage won't have a problem getting a full understanding of an artifact from the post-destruction residue, or be bothered by the background magic from his own castle.

Indeed, neither the background magic nor the diary being inert poses any problem whatsoever. The diary itself, on the other hand. Dumbledore takes the diary when Harry holds it out, but his frown is already deepening before he sees it.

"Yes, it's fully destroyed now. Basilisk venom is a potent substance. Miss Weasley, you have from the sound of it had a very long day. I recommend you go to the hospital wing and let Madam Pomfrey look you over and prescribe a mug of hot chocolate and a good night's sleep."

"Then--I'm not in trouble?"

"Certainly not. Wizards much older and more experienced than you have been hoodwinked by Lord Voldemort. And his other victims should all have received their mandrake draught by now, so no harm done in the end."

Wobbly but genuine smile.

"Hermione's awake, then!"

"Just so. Perhaps you could escort your sister to the hospital wing and pay her a visit. And Minerva, I think all this merits a feast. Perhaps you could alert the kitchens. Harry, Samora, if you would remain here a few moments longer?"

Everyone with the surname Weasley departs in reasonably good spirits.

Likewise.

Dumbledore smiles at Harry. "You must have shown me real loyalty down there in the Chamber. Nothing but that could have called Fawkes to you."

"And you met Tom Riddle. He must have been very interested in you."

"Yes . . . Professor, why did Riddle say we were alike? Why do I speak Parseltongue? Why do I show up to Samora's evil-detecting spell?"

"You can speak Parseltongue, Harry, because Lord Voldemort--who is the last remaining descendant of Salazar Slytherin--can speak Parseltongue. I believe he unwittingly transferred some of his power to you, the night he gave you that scar."

"Voldemort put a bit of himself in me?"