Disclaimer: I own nothing, none of this is true.
Summary: Dark!fic. There is a point where everyone breaks, unfortunately for the Dursley's, Harry has just reached his. Set when Marge visits in POA.
Author's Note: Sorry guys, I suck. Hope this makes up for it, maybe?

Rational Conversation

Harry laughed, delighted. It was all going to plan, what plan, exactly, he wasn't sure, but it all seemed to be falling into place. The Black's tempers were majestic when roused and if he could keep hitting the right buttons, he would soon have this Black firmly under his thumb.

He yawned widely, stretching like a satisfied cat. With everything set in motion he could finally get some rest. He stood only to fall back into his seat with a choked off scream of pain. It felt like fire was coursing through his body. He bit through his lip in an attempt to stifle is cries of agony as the protective coat of magic that had been covering his injuries vanished. Every bruise, cut and break that his aunt and cousin had given him flared to life at once. Now that he was alone and temporarily safe, his magic changed from hiding to healing his beaten body. Finally the pain became too much and he slumped forward, unconscious.

Break.

When Harry woke he felt weak, drained. The darkness was quiet and passive, having been pushed back by his magic in its rush to fix him. He whimpered with residual pain and stood stiffly.

His mind was conflicted.

"I've just killed four people," he whispered into the silent kitchen.

Break.

"I'm not stupid, I know dark magic when I see it and that is definitely dark magic that is weeping from your scar and collecting around your heart. Tell me, Harry, please."

A vulnerable frown spread across Harry's face. No matter what changes were happening, he was still only thirteen years old. The old Harry was still in there, curled up in a smothered, frightened ball, too exhausted to fight the malicious tendrils taking over his body, mind and soul.

"I have knowledge, memories that aren't my own."

Sirius waited patiently, moving over to the table to sit back down. He'd spent the entire night thinking. He would not let his rage take over his mind this time. He had already made that mistake once; he would not allow it to happen again. He was an adult and he had to be responsible and rational for this child, no matter his own feelings and old hurts, he had to do this for Harry.

"Horcrux." Sirius sucked in a sharp breath. There was a moment of stillness. "I can feel it consuming me," he whispered, "slowly but surely." He raised his eyes to meet Sirius', releasing a wobbly laugh. "Don't forget to breathe."

Sirius let out the air into a shaky sigh. "Horcrux," he parroted, his face settling into a grimace. "That explains a lot. Humans are never made into horcruxes for a reason. When an animal horcrux is created, they become an extension of their creator. The owner of the soul piece can possess them and control their every action if they so wish it."

"So it set me free from the abuse of my family but is also going to be the thing to destroy me?" Harry asks with a humourless chuckle.

"More or less. I really think you need to tell me what happened now."

"You're disgusted by me."

"No. I'm disappointed that you were so physically beaten down and mentally crushed enough to leave an opening that would let this darkness in-"

"Was too weak and pathetic to stop it, you mean." Harry cut him off bitterly.

Sirius continued as if he hadn't heard the interruption, "-let it control you and destroy the good that I know had to have been in you before." They both looked across the table silently, each studying the other. "Weakness has nothing to do with it, even that strongest men can fall to the darkness with less of a push than what you have suffered." Sirius whispered sadly.

"What? The darkness I have suffered? From the horcrux, you mean? You have no idea!"

"I know suffering! Have you ever met a dementor? Do you know what it's like to only have fear, bitterness and hatred for twelve years? To be cold inside and out with no hope that it will ever end? To know that people think you are a murderer, that you are responsible for the deaths of the only people who ever thought you were worth something, who looked past my family and saw me. They were my best friends, the most important people in my life and their murderer is still out there! Out there with a family, living his cosy life as a rat, the filthy traitor. All because of me. My mistake. My misplaced trust. Me. So not only have I been tormented by the dementors that constantly surrounded my cell in prison, that is nothing compared to the torment I have received from myself."

"So we have both spent twelve years in hell."

"They were cruel to you, your relatives?"

"Yes. They are – were – the worst kind of muggles. Hated magic, hated my parents, so therefore, they hated me," Harry explained shortly. He never wanted to think about them again. If he could just forget about them, he could forget how their lives ended, what actions they pushed him towards, what those actions had made him feel. His heart clenched painfully. The hate may have been mutual, but he had never thought he was capable of cold blooded murder.

"I- They- What is happening to me?" Tears pricked in his eyes as he glanced at anything but Sirius. He was changing and he was scaring himself. Only a day ago, murder was the worst kind of sin, now he had committed it himself and had liked it.

"All that is and was you is being consumed. Horcruxes weren't made for people. People are too complicated to hold them. For twelve years you've had this piece inside you that has been resting on a knife edge and it has finally fallen. It found the weakest point of your subconscious, your mind wanted something to save it so it welcomed it and it wormed it's way in, taking control, morphing and mutating you until there will be nothing left."

"How do you know all this?"

"The Black's aren't considered one of the darkest families for nothing," Sirius replied with a bitter twist to his mouth. "My mother made me learn all that she thought was necessary for me to know and it wasn't about rainbows and fairies."

Harry huffed out a laugh before the seriousness of his situation rose back up to forcefully dampen his humour. "What is going to happen to me?"

"I- I don't know."

"You do. Do not lie to me!"

Sirius sighed, eyes desperately sad.

"Tell me."

"Your body wasn't made to contain more than your soul, small fragment or not, it will still be too much to handle. While it is consuming all that you are on the inside, I fear it will also do the same to your physical presence."

"So what you're saying is I'm going to die?" Harry asked, voice choked. Sirius looked away, unable to voice what they both knew was the answer to that question.

"We'll find a way, we will…"