deterioration
By Monday morning, Harry knew he couldn't go into work. He'd spent the weekend alternating between hiding his symptoms from Ginny and lying in bed when she was out, consumed by fever and pain. The black veining had spread further, now creeping down his cheek and up into his hairline. No glamour charm seemed to last more than a few hours before his own unstable magic disrupted it.
"I'm staying home today," he told Ginny as she prepared to leave for an early morning practice. "You were right—I need rest."
Relief washed over her features. "Good. I've left some pepper-up potion in the kitchen. I'll check on you at lunch."
As soon as she left, Harry dragged himself to the small library they'd established in the renovated Grimmauld Place. If this was something related to his scar—to the piece of Voldemort's soul that had once resided there—perhaps there would be answers in the books on Dark magic they'd kept.
Hours later, surrounded by open tomes and scrolls, Harry found something that made his blood run cold. In an obscure text on magical remnants, there was a passage about "curse echoes"—the phenomenon where powerful Dark magic could leave traces even after the original curse was broken.
"In rare cases," he read, his vision blurring with fever, "when a curse of sufficient power has long inhabited a living vessel, it may leave behind a magical residue that eventually becomes toxic to the host. The host's own magic begins to attack these remnants, but in doing so, can trigger a cascading reaction akin to a magical autoimmune response. Without intervention, this process inevitably leads to magical destabilization, physical deterioration, and ultimately, death."
The book fell from Harry's numb fingers.
A soul fragment had lived in his scar for seventeen years. If any curse would leave behind toxic remnants, surely that would.
As if triggered by this realization, a wave of pain unlike anything he'd experienced before crashed through him. Harry doubled over, clutching his head as the agony built to an unbearable peak. Something warm and wet trickled down his face—blood from his scar, vivid red against his palms.
He needed help. He needed to tell someone.
Harry crawled toward the fireplace, intending to Floo call Hermione, when another spasm hit him. This time, his magic reacted violently. Every object in the room levitated suddenly before crashing back down. Windows shattered. Books burst into flames.
With the last of his strength, Harry managed to cast "Aguamenti!" to douse the burning books, but the spell emerged as a violent torrent, flooding the room with far more water than he'd intended.
Soaked and shaking, he collapsed onto the floor, darkness creeping in at the edges of his vision. His last coherent thought was that he should have told Ginny the truth from the beginning.