"The Cloak?" wonders Ellen.

"Right, I said I would explain the Deathly Hallows--let's start with the bedtime story version," she says. "Once upon a time, three brothers were traveling through a forest. They came across a great and fierce river, that no man could hope to swim across and survive. But the brothers were powerful wizards, and together they conjured a strong bridge, over which they passed the river safely."

Death was annoyed that they had evaded him, since the river had taken the lives of many travelers. But Death is cunning and subtle, so he congratulated the Brothers on escaping him, and offered each of them a boon."

The oldest brother asked for the most powerful wand on earth, so Death took a branch from a nearby Elder tree, and fashioned a wand, and gave it to him. And the first brother, pleased with his prize, went to find another wizard with whom he had a quarrel, and slew him, and boasted in the tavern that night that he had the most powerful wand on Earth. So another wizard crept into his room that night and cut his throat as he slept, taking the Elder Wand for his own. Thus did Death claim the first brother for his own."

The second brother asked for something that would allow him to pluck people from Death's own grasp. So Death picked up a pebble from the riverside and gave it to him, saying that if he turned the stone over the one in his thoughts would be returned to him. So the second brother returned home, and summoned the shade of a woman he had once loved, and lived with her for a time. But he was dissatisfied with being unable to be with her completely, so he ultimately killed himself to be with her in truth. Thus did Death claim the second brother as his own."

The third brother asked for something that would hide him from Death himself. And so, reluctantly, Death removed his own Cloak of Invisibility, and gave it to the third brother. And Death could not find the third brother for years and years and years, until the third brother was very old. The third brother gave the cloak to his son, and finally departed with Death as equals." 

"It's nonsense," Antioch harrumphs. "It took me way more than one night to get myself killed." 

Ignotus elbows him. "More importantly, Death didn't give us anything. We created the Deathly Hallows ourselves."

"Interesting!" she says thoughtfully. It's not quite like any specific legend she's heard but it sort of rhymes with a few - something something Hades's helmet, that sort of thing. "I wonder how that managed to be the way your accomplishments were remembered?"

"Good question," Ignotus says. "The story didn't become popular until long after I died, so none of us have a direct perspective on it." 

Eurydice shows Ellen the Stone. "This is the sigil of the Deathly Hallows, see? The triangle is the cloak, and the circle is the stone, and the line is the wand." 

"What was their original purpose as a set—and why are they themed around death?"

"The purpose of all of them was to fix Death," Cadmus says. "They were the first phase of what was originally planned to be a project to deal with it entirely." He gives Antioch a judgmental look. "When Antioch got himself killed as a braggart, and the Wand was lost, it was--a setback. A very large setback. The Elder Wand is powerful. It's not meant for dueling, it's meant for bootstrapping creating more artifacts."

"The thing we objected to wasn't the afterlife," Antioch clarifies, looking embarrassed at being called out like that. "It was Death as a process, the way it currently exists, where everyone starts out on Earth and then ends up in the afterlife and then can't go back or even communicate with anyone back on Earth." 

"We kept going, after Antioch died, but...it wasn't just the loss of the Elder Wand," Ignotus says. "We had access to fewer ideas back then--the thing that amazes me the most about the modern world, especially modern muggles, is the information technology they have. The printing press! The radio! Angelica has been very patient about explaining these sorts of things." 

"Wait'll you hear about the Internet," Ellen murmurs with a smile, glancing over at the laptop for which there is no longer any room on her desk because her desk is instead covered in lab equipment.

"What's the Internet? And what's that thing, too, for that matter, I assume it ties into this Internet thing in some way."

She holds up the thoughts for Eurydice to examine—blurry memories of sitting at a desk with a glowing screen in front of her, scrolling through Wikipedia, opening new tabs to follow interesting references—as she goes to open up said laptop for a practical demonstration.

"In short, information technology that improves on the printing press more than the printing press improved on clay tablets. In slightly less short—you have radios in your world, do you have telegrams? The basic concept of sending information over a wire, so that text signaled at the origin arrives very quickly at the destination? That, but faster. So much faster that you can send entire books across a continent in seconds or minutes. And the technology developed in tandem with devices like this," she opens the laptop and demonstrates typing into a text editor, "which can access and display and manipulate the information, also in novel and powerful ways."

"Whoah. When does this happen? --Ooh I bet you anything tech class involves even better versions."

Ellen grins. "Yes, I very much expect it will!"

"You had better figure out a safe way to get me into the library," Ignotus mutters. 

"Can ghosts interact with physical objects at all? I wonder if I could make a tracking interface of some kind... I wish we'd brought more hardware expertise, I only have a partial set of our skills for security reasons." She nevertheless rifles through her collection for brains she has absorbed that might be able to help with the task, which is a deeply disorienting mental motion to experience at one remove. Like watching a highly compressed montage of someone paging through book after book after book, except that each book is a whole person with a lifetime of experiences, all going by in a flash as Ellen picks them up and then puts them down again when they don't contain the thing she wants. Absently, out loud, she explains, "If you can't move things around but you can be detected by cameras, I could probably rig up something that would let you use a computer yourself despite being insubstantial. Best to keep that in the room, though, hidden from prying eyes so they won't know we have a team of ghost researchers backing us up."

"We can't exert force," he says. "We can be detected by cameras."

"I have to turn the pages for them when they're reading books," Angelica says, "but that's still faster than reading everything myself."

"It might take a bit of trickery to actually implement, but in theory, if you can be detected by cameras then you can use computers and if we come up with enough computers you can all be reading different books simultaneously with no one having to turn pages for you," says Ellen. "Now that's what I'd call a force multiplier."

"--I wonder what happens if there's six of me and one gets addicted to a magical substance," Eurydice speculates. 

"Please do not get addicted to Felix Felicis," Merope says. 

"But Moooom, it's so useful." 

"Oh, I have lots of advice for separating out duplicates to try getting addicted to things," Ellen says cheerfully. "Not magical things, admittedly."

"You should try Felix Felicis. --Mom will you chill out if she tries getting addicted to it first and it works out okay?"

Merope makes a long-suffering face. 

"Felix basically tells you what to do next to get the best results, I wouldn't want all of me to be on it all the time but it's so fucking useful."

"I'll think about it. How easily can you repeat that pig trick? And how does Felix decide what the best results are and how you should get them? —And we really should go get dinner at some point, we're feeding three people now and shouldn't get in the habit of skipping or delaying meals because we're distracted by interesting ideas." (Ellen has a lot of experience getting in that habit and then needing to get herself back out again.)

"Excellent point. Eventually I'll have to brew more Fuming Philtre but that's pretty much the bottleneck on the pig thing," Angelica chimes in. "We don't know exactly how Felix works yet." 

"Is 'how does Fuming Philtre work to produce pigs' the sort of interesting but largely strategically irrelevant question we could discuss on the way to dinner?" she wonders.

"Fuming Philtre doesn't directly produce pigs--yes, it very much is, let's go." Giggle. "I'll even go first, if you still care."

"Not in the slightest, but it's amusing," she says cheerfully. "After you."