A/N: Hiya, Green Feather here! This story is an AU taking place during Kingdom Hearts 2, but you should keep in mind that some changes were also made to what happened during Chain of Memories and the time Sora spent asleep.

The only change relevant to the prologue, though, is that Sora obtains the Two Become One keychain from Roxas when the two unite and Sora awakens, at the start of KH2. If you didn't know, having it equipped in KH2FM nets you a permanent 75% chance of entering Anti Form (the remaining 25% will always give Final Form).

"An image of you overcome by the power of darkness flows into your mind."

Sora wasn't stupid enough to believe there was only light in his heart, but when the mirror in Yen Sid's tower showed him that horrible image of himself shrouded in darkness he had quickly looked away and tried to distract himself with something else. That was when he had realized he should have tried out the strange keychain he had found himself holding when waking up in that creepy room.

Summoning his Kingdom Key in one hand and the keychain in the other, he had attached it to his keyblade and then removed the one representing the King's head. Instantly his weapon had changed form and Sora felt power flow through him and give him a feeling of completeness he had never experienced before. Staring in awe at what he could feel was called Two Become One he had tried swinging it around, almost cutting a few feathers out of Donald's tail in the process.

"Are you trying to kill me?"

"Sorry, Donald..."

With a sheepish smile and a scratch on the back of his head, Sora had then made his keyblade disappear, getting ready to head back to the Gummi Ship and officially set out for a new adventure.

- . - . -

What was only weeks ago now felt like years to Sora, who was lying on his back on the ground, in the outskirts of the city of Hollow Bastion. The last strands of darkness still clinging to him.

The first time it happened they were visiting Halloween Town, and while investigating the Graveyard a large group of Heartless had attacked them. Sora had lost track of Donald and Goofy shortly after the start of the battle, but wasn't worried since he could still hear them yelling spells not far from him, so he decided to make the most out of the battle and collect as much Munny as possible.

Too concentrated on gathering money, Sora didn't immediately notice a new wave of Heartless coming from all directions and completely surrounding him.

The Wight Knights seemed to never end, and ten minutes later the keyblade hero was getting tired. Thrust, strike, slash, slash, heal. After casting Cura on himself for what felt like the milionth time and slashing through one more Heartless, Sora suddenly felt something calling out to him. It was powerful and not completely foreign to his senses so he trusted his instincts and called back to that power.

Suddenly his hands were free. But it didn't matter, because he felt free. His movements were faster than ever, the enemies didn't have a chance to hit him now, he could dodge anything and attack back immediately, scratching, kicking, scratching again. After some time, a jump and a blast of dark magic took care of the remaining Heartless, but Sora wasn't satisfied. He wanted more, he needed something, someone was yelling, his instincts and feelings were getting mixed and confused. Holding his head between his clawed hands he fell on the ground and everything went quiet.

When he came back to his senses, Donald and Goofy were looking at him from above with worry in their eyes. He groaned and tried to stand up, but managed it only after his friends used a Potion on him.

"What happened?" He could remember it too well.

"You worried us to death! When we finished taking care of those damn Heartless we found you lying on the ground!" They didn't see anything strange?

"I'm fine now, we should keep exploring."

- . - . -

He could feel one last Shadow approaching him. He tiredly held up his hand.

- . - . -

It had happened another couple of times after the first one. He couldn't help it; when he felt that power call to him, he instinctively answered it.

Being in that form made him feel somewhat feral, but the truth was that he was almost completely in control of himself. He couldn't turn back at will, but he knew perfectly well what he was doing. Fighting came more natural than ever, and the lack of his keyblade could be easily fixed by ripping Heartless to shreds with his own hands. The method was a bit savage, but hey, whatever works.

So far, the only real drawback of borrowing the power of darkness was that afterwards he always felt hungry.

Sora tried his best to convince himself that sudden hunger was the only wrong thing in this whole mess. As long as he could keep himself in control and be lucky enough to avoid Donald and Goofy finding out about his problem, everything was fine.

- . - . -

Being sure that nobody was around to see him, instead of summoning his keyblade he smashed through the little Heartless with his bare hand. He didn't even twitch at seeing that his hand was black and clawed.

He really needed to stop this.

But first, he needed to find something to eat.

A/N (2): Concrit and every other review would be really appreciated! As I don't have a beta and only proofread this myself, if you notice some awful typo or grammar error it'd be nice if you were kind enough to point it out in a review or a PM! I am not a native English-speaker and can make horrible horrible mistakes without ever realizing it.