The ruins were four days in, when Bill determined they had acclimated sufficiently to manage a full day outside Cairo.
Saqqara first.
The Step Pyramid rose from the desert plateau with the indifference of something that had been there for four and a half thousand years and had long since ceased to require anyone's acknowledgment. He stood at its base and looked up and felt something he hadn't felt since arriving in this world — the specific quality of smallness that came from standing next to something that had genuinely survived time in a way that very few things had. Not old in the way that Hogwarts was old, or the Chamber was old. Old in the way that preceded the things those things were old relative to.
He had felt something adjacent to it holding the basilisk fang. He felt it here, differently but from the same direction.
Bill was beside him.
"First time it really hits you," Bill said, looking up at the pyramid.
"What does?"
"That everything you know is recent," Bill said. "That history is this long —" he spread his arms wide "— and most of what people treat as old is about here." He held two fingers very close together.
He thought about a divine being in a white void speaking about the multiverse with the calm of something genuinely ancient, and thought that his sense of scale had been recalibrated in ways that were still settling.
"The magical archaeology is even older than the Muggle," Bill said. "The curse work in some of the sites predates the written magical record. We find things we can't identify regularly."
"What do you do with them?"
"Document them," Bill said. "Contain them safely. Sometimes bring in specialists. Sometimes mark the area and come back when we know more." He paused. "The honest answer is that we often don't know what we're dealing with. The work requires a very high tolerance for uncertainty."
He thought about objects that had been made into something they weren't meant to be. About wrongness that didn't announce itself on the surface. About a diary that had contained fifty years of a fractured soul and had looked, to the uninformed eye, like a diary.
"Bill," he said.
"Yeah?"
"Has Gringotts ever encountered objects that weren't right?" He chose the words deliberately, approaching it from the direction of someone feeling toward a concept rather than one who had arrived at it. "Not cursed in the conventional sense. Something more — fundamental. Objects that had something done to them that made them wrong in themselves."
Bill was quiet for a moment. The desert stretched around them in every direction, the sky above it the specific blue of a place with no humidity to soften it.
"Junior curse breaker," he said finally. "Two years in. I've encountered maybe three things in that time that I couldn't explain to my own satisfaction — that I flagged to seniors and was told to leave for people with more experience." He looked at the pyramid. "Why are you asking?"
"The diary," he said. "Last year. Whatever Riddle was — whatever it was doing to Ginny. I've been thinking about it since the Chamber. It wasn't a normal curse and it wasn't a normal enchanted object."
Bill's expression changed. Subtle but real — the shift of someone who had been turning something over privately and was having it named from outside. "I know," he said quietly. "Mum wrote to me about it. I've been thinking about it too." He paused. "It's beyond my current expertise. But it's not beyond Gringotts'. I've flagged it as a research interest to the senior curse breakers in my division. If anything comes up in the literature — dark objects with similar properties — I've asked to be notified."
"There might be more of them," he said. He said it carefully, in the tone of someone sharing a suspicion rather than a certainty. "I don't know. But the way it worked — I keep thinking it wasn't a single project."
The silence that followed had weight, the way silences did when the thing not being said was significant enough to make its absence felt.
"I'll look into it properly," Bill said. Not lightly. With the gravity of someone who had understood the implication and was making a commitment accordingly. "It might take time. The literature on this kind of object is not exactly the kind of thing Gringotts keeps in the main archive."
"I know," he said. "I'm not in a hurry." This was not entirely true, but it was true enough that he could say it honestly. "I just wanted someone who might find something to be looking."
Bill nodded. They stood in the desert for a moment longer, looking up at the pyramid, and then Bill's mother called from somewhere behind them that they were going to miss the sand-walking demonstration if they didn't come now, and the moment converted itself back into a family holiday with the easy efficiency of a family that knew how to do that.
They went to Karnak three days later, and then to the Valley of the Kings, and then — on the last full day before Cairo — to a site that Bill knew through his work and that was not on any tourist itinerary because the relevant authorities had decided that mixing magical and Muggle archaeology in a single tourist experience created complications that outweighed the benefits.
The site was pre-Ptolemaic. Old enough that the ward work on it had been laid down before the systems Bill had learned to read, which meant he was working partly from pattern recognition and partly from the survey text he'd found in the Cairo magical district, and partly from the specific instinct of someone who had been reading magical structures for two years and had developed a feel for them that preceded explicit knowledge.
He walked through it with his wand out and his eyes open and the ward text in his head and felt the specific pleasure of things clicking into place.
The rune sequences here were not identical to anything in the Hogwarts curriculum or in Bill's working texts, but they were related to them in the way that dialects of the same language were related — different enough to require active translation, similar enough that the translation was possible. He worked through them slowly, checking his readings against Bill's, asking questions when he wasn't certain and answering them when he was.
"That sequence," Bill said, pointing at a carved section of wall that looked, to an uninformed eye, like decorative hieroglyphs. "What's it doing?"
He looked at it. Thought about it. Cross-referenced the patterns against what he'd learned over the previous week and the theoretical framework he'd built from the curriculum texts and the pensieve memories.
"Layered detection ward," he said. "The outer layer registers presence. The second registers intent. The third —" he paused, working through the more complex sequence "— the third does something to intent-classified threats. Not harmful. Redirecting. It changes the spatial perception of whoever triggered it."
Bill looked at the sequence. Looked at him. "That's fifth year reading."
"Is it right?"
"Yes," Bill said, with the tone of someone updating an assessment in real time.
"The logic follows from the second year foundation," he said. "Once you understand what the base runes are doing, the extensions are consistent."
Bill was quiet for a moment. "How much time do you spend on this?"
"Every evening of the trip," he said. "Two hours. Sometimes more."
"And before the trip?"
"The Room of Requirements at Hogwarts," he said. "One month of evenings. The second year curriculum first, then the third year theoretical material."
Bill looked at him with the full weight of the assessment he'd been building since the first evening of the trip, when he'd sat down with the working texts and begun correctly parsing things that had no business being correctly parsed by someone two years into the Hogwarts curriculum.
"You're going to outpace me within a few years," Bill said, with the specific tone of a craftsperson who had found someone with genuine aptitude and found the prospect interesting rather than threatening.
"I have a long way to go," he said.
"Yes," Bill agreed. "But the way you go."
He didn't respond to this, because it didn't require a response, and because the site around them was asking for attention and he intended to give it.