The peace that followed the successful dinner party was a warm, golden thing. For two weeks, they settled into a new, blissful rhythm. Mornings were for their separate Ministry work, afternoons and evenings were for each other and the Vault. They worked side-by-side, their collaboration now effortless, a seamless dance of her logic and his intuition. Evenings were spent in her flat or his, talking, reading, or simply existing in a comfortable silence that felt more intimate than any conversation.
It was perfect. And that, Hermione should have known, was when things were most likely to go wrong.
The trouble began with a memo. A bright yellow memo from the Department of International Magical Cooperation, fluttering onto her desk like a poisonous butterfly. It was a request for a preliminary briefing on the Aethelred Vault for a delegation of wizards from the Brazilian Ministry, experts in ancient earth magic. They were visiting in a month, and the Department Head thought it would be a "splendid opportunity for cross-cultural exchange."
Hermione saw it for what it was: a political move. A chance for a bureaucrat to show off a shiny, mysterious new discovery. She was annoyed, but she saw a potential benefit. Fresh perspectives could be useful. She brought it up with Cassian that evening in the chamber.
"The Brazilians have some of the most advanced understanding of geomancy in the world," she said, leaning against the worktable. "They might see something we've missed."
Cassian didn't look up from the folio, where he was comparing one of the sorrow-symbols to a fluctuation in the Vault's resonance. "No."
The word was flat, absolute.
Hermione blinked. "What do you mean, 'no'?"
"I mean no," he said, finally turning to face her. His expression was already closing off, the shutters coming down. "This isn't a zoo exhibit. We are not putting its grief on display for a group of strangers to gawk at."
"It's not gawking, it's collaboration!" she argued, her own temper beginning to flare. "We're stuck, Cassian. Your theory is brilliant, but it's still just a theory. We need data. They could help."
"We don't need their help," he snapped, standing up. "We've managed perfectly well on our own. This is our work. My work. I will not have it picked apart by a committee of foreign bureaucrats."
"Our work?" she shot back, stepping towards him. "A moment ago it was your work! This isn't just about you and your precious theories! This is a Ministry project. There are protocols. There's a chain of command!"
"Since when do you care about the chain of command?" he retorted, his voice dripping with scorn. "Since it gives you an excuse to hand over our discovery to the first group of outsiders who ask?"
"That's not fair! I'm trying to be practical! To move this forward!"
"By diluting it? By turning it into a… a diplomatic cocktail party?" He ran a hand through his hair in frustration. "This is why I work alone. No committees. No pointless meetings. No one to compromise with."
The words hung in the air, sharp and cruel. No one to compromise with.
Hermione felt as if he'd slapped her. "Is that what I am?" she asked, her voice dangerously quiet. "A compromise?"
His eyes widened slightly, realizing his mistake, but his pride wouldn't let him back down. "That's not what I meant."
"It sounds exactly like what you meant!" Her voice rose, echoing in the chamber. "You can't stand the idea of anyone else touching your brilliant discovery! You'd rather let it sit here, frozen in time, than risk someone else getting credit or, Merlin forbid, having a better idea!"
"This has nothing to do with credit!" he roared, his control finally shattering. "This is about respect! For the magic! For the loss it contains! You want to bring in a bunch of strangers with their scanning spells and their theories and their… their small-minded curiosity and let them poke and prod at a wound that's older than their entire civilization!"
"And you want to keep it locked away like your own private treasure!" she yelled back, tears of frustration stinging her eyes. "You're so afraid of being wrong, of being challenged, that you'd rather be stagnant than risk being proven incorrect!"
They stood glaring at each other, chests heaving, the air crackling with their anger. The Vault hummed placidly in the background, a silent witness to their first real battle.
"This is who you are, isn't it?" Hermione said, the fight draining out of her, replaced by a cold, weary sadness. "The solitary pursuit. Pushing people away. I thought… I thought we were past that."
She turned and walked towards the door.
"Granger—" he started, his voice strained.
"Don't," she said without looking back. "Just… don't."
She left him there, alone in the chamber with his principles and his pride. The heavy door swung shut, and this time, the silence on the other side felt different. It wasn't the peaceful silence of shared purpose. It was the cold, empty silence of a bridge burning.