"But it's destroying Voldemort's support base," Ron said, genuinely puzzled. "Isn't that good?"
"That's the bonus. The cover story." Kevin kept his voice even, turning the idea over. "Think about where it actually leads. Not this year. Not the next. Ten years from now. A century."
Harry frowned. "What do you mean?"
"It starts with separation — which sounds reasonable, if you're scared of Muggles. But separation doesn't stay neutral. Every year you're apart, the distance compounds." Kevin looked around the group. "Think about what Ron said. Muggles, given time, would seek out magical spouses if it meant magical children. The pure-bloods aren't wrong about that."
"So if you want those families to stay pure-blood for good," he continued, "you can't just separate. You have to make Muggles unthinkable. You smear the image. Consistently. Loudly. Until the idea of a Muggle being anything other than a threat is completely alien."
The rain drummed on the awning.
"You build enough resentment, keep the populations apart long enough, give the hate fifty or a hundred years to ferment — and then, when the next dark wizard comes along and lights the fuse, you don't get a divided war like Voldemort's. You get something unanimous. Something with popular support. Something that doesn't stop."
The silence around the table had changed quality.
Sirius had stopped eating.
"You're saying," Harry said slowly, "that whoever's spreading this idea isn't trying to help Voldemort. They're trying to make sure that the next Voldemort wins."
"Or that there doesn't need to be a next Voldemort. Just a world where the conditions are ripe enough that the war starts itself." Kevin picked up the tongs again. "Lose the short game? Fine. You've still poisoned the well for the next century."
"We tell Dumbledore," Sirius said. He'd been quiet, listening, and his voice when it came was certain.
He crossed to the tent entrance and was already composing the letter in his head. The others watched him, then looked back at Kevin.
"Is this definitely what's happening?" Harry asked.
"Could be wrong," Kevin said. "But it fits. And I'd rather be wrong and wrong loudly than right and quiet about it."
The letter went off.
The barbecue continued.
An hour later, the doorbell rang again.
Draco stood on the porch, soaked to the skin, dripping on the welcome mat. He had the expression of someone who had run through a rainstorm because it was preferable to whatever was behind them.
"Kevin." He looked past Kevin at the others piling up in the hallway. "That old man who fought you at the Manor last semester."
"He's been staying with us the whole summer."
"I couldn't write. Couldn't leave. He went out this morning and I came straight here." He took a breath. "His name is Gellert Grindelwald."
The hallway went completely quiet.
"He's at the park," Draco continued. "Central London. He's called a meeting. All the wizards in England. Now."
He was already turning back into the rain.
Kevin was moving before anyone else was, his coat off the hook in one motion. Over his shoulder, to Harry: "Message Dumbledore. Now."
Harry already had his wand out.
They ran.