The world had gone to hell. There was no denying it. Both the Wizarding and Muggle worlds had been affected; the hard line between them had been soundly shattered within the last few years. Not that anyone really cared about the existence of magic any more, not when it was so rapidly draining from the world.
The loss of magic had started, as do many things like it, with good intentions. The past century, it was reasoned, had been overshadowed by two of the worst Dark Lords in history. What better way, then, to make sure it never happened again than to stop it before it started? After all it was a well-known fact that those with an affinity for Dark Magic were born with it, so why not tackle the problem at the source? The Department of Mysteries were set on the problem, and two years after the final death of the Dark Lord Voldemort, they released their solution into the world.
It worked for all of two months before the magical disease began to mutate beyond their wildest nightmares.
Those with an affinity for Dark magic fell ill first, mainly the adults who had been producing magic for years. The children began losing their magic next and then-- And then, it jumped to those attuned to Gray magic, something the sickness' creators had never imagined it might do. Prominent members of the neutral faction began losing their magic, leaving the Wizengamot even further drained of its seated members.
The disease then jumped to both those with an affinity for Light magic and the world of the Muggles. Thousands died in Great Britain alone, given the high rate of Squibs that had intermarried with Muggle lines over the years. It was labeled as a pandemic three months after it was released. Scientists and experts were baffled by both the virulent plague and the fact that it acted like no known disease, either historical or current. It attacked the magical cores of the afflicted first, followed by more mundane systems. In the end, the afflicted wasted away due to extreme dehydration and malnutrition, no matter what methods were employed to combat those symptoms. Once someone who was infected stopped voluntarily eating, they had maybe two weeks to live at most.
With so many dying, the world's governments were hard-pressed to devote resources to extraneous projects or keeping infrastructures intact. It wasn't long before fights, battles, and then finally a series of desperate wars broke out amongst the nations, each seeking to lay the blame on someone.
London and the surrounding areas soon returned to the state they'd been in during the Blitz. Those that survived turned into scavengers, living in the broken and burned out remains of once-bustling buildings. Three such survivors had taken up residence in what had once been an Underground Station near King's Cross. It was protected from the elements and other people, which made it perfect for them.
Late one night, one of the three came back to the Den, as they'd taken to calling the hideaway, a half-filled rucksack slung over a shoulder holding the meager results of his scavenging run. The rudimentary wards at the entrance brushed over him before letting him through, going quiescent once more after he'd passed.
“Draco? Harry? I'm back!” he called out as he stepped off the rubble-strewn stairs.
“Over here, Neville,” Harry called back. He was sitting beside the blanket-covered form of Draco, who was glaring halfheartedly at him from his position on the thin mattress on the floor.
“Still being a stubborn ass?” Neville asked in fond amusement as he set his bag down and then began to take his shoes off.
“Yes,” Harry said. At the same time, Draco tried to protest with a “No!” that was interrupted by a bought of coughing. Harry just sighed and then handed him an open bottle of water to sip on after the coughing was done.
“We're doing it tonight,” Harry said. “We don't have much longer, and it's the perfect time to do it given how thin the Veil is at the moment.”
“I hardly have any magic left,” Draco rasped. “Even with the bond--”
“We have enough magic for this,” Neville interrupted. “If it works, then we'll be able to change so much, and hopefully for the better. If not...” He shrugged. “Well, it'll hardly matter, given how the world is. Either way, we'll be together, and that's what matters the most.”
“Sentimental lion,” Draco muttered, though there was hardly any heat behind it.
“Stubborn snake,” Neville retorted, reaching out to take hold of Draco's free hand. They stayed like that for a long while before Harry started to get things ready for the ritual. Half an hour later, he finished setting everything up. The potion they needed to take had been carefully brewed during the last full moon using precious ingredients that had been found in an abandoned apothecary in Diagon Alley. It was kept waiting in three opaque bottles that sat nearby.
Harry kept an eye on his cracked watch, and when it was five minutes to midnight, he gave Neville and Draco their bottles before taking his own. He downed the surprisingly sweet-tasting brew before laying down on Draco's left. Neville mirrored his actions, setting his empty bottle aside before laying down on Draco's right. The three wizards began chanting in practiced unison one minute before midnight, the spell finishing with a thunderous crescendo right as the clock struck twelve.
The explosion that Halloween night leveled three city blocks and left a crater fifty meters deep at the center, with not a trace of what had caused it left behind.