Title: The Demon Within
Rating: K+
Summary:When an old enemy breaks his promise and hurts Sanji, Zoro decides he has to take revenge, while Robin's not so sure.
Words: 939
Acknowledgments: This is an unanon from the One Piece fan-for-all, so thanks to the OP over there for their interesting dark!Zoro prompt.

"Are you sure about this, Swordsman-san?" Robin's voice is low and level, but even he can detect an undercurrent of anger in the archaeologist's normally calm voice. "Luffy did say..."

"I know what he said," Zoro interrupts. "And that psycho bastard Gobei had his chance. Look what he did with it." He glances down at the bloody body of the cook, cradled as gently as Zoro can manage as they sprint through the narrow streets, and another swell of pure rage rolls through his brain. Sanji's already irregular breathing hitches and Zoro forces himself to rein in his bloodlust, knowing the cook's too weak right now to bear it.

Robin senses the diminution in the dark aura and takes a surreptitious glance at the swordsman. For a moment there, he had her frightened - she'll admit it, to herself but to no one else. She's felt his enmity before, in those jet black eyes that bore straight through to her soul, in the way he would crack one eye open in the middle of a nap to glance over her way, warning her that he was watching, promising that the slightest hint of betrayal would be met with swift retribution, but never this. She supposes she should be - flattered? reassured? thankful? - that his feelings towards her from the very beginning were never wholly negative, that he had always given her the benefit of the doubt. She knows that now, now that she knows what he's like when he's really, truly angry.

Demon. The word floats to her mind, and she's instantly ashamed of labelling him the way she was once labelled. No demon would allow himself to be manipulated the way Zoro lets himself be manipulated by Nami. No demon would watch with a smile as the three youngest Strawhats caper around in one of their rambunctious games, much less let himself get dragged into one. No demon would endure agonies that should have been the death of him, for the sake of anything other than his dream.

And yet, there is a part of her that thinks the label is wholly justified in Zoro's case, now that she's felt the terror that earned him the appellation "Demon of East Blue". She can't help but feel there's a whole other side of him that he's careful never to let the crew see, a roiling tide of fury kept in check only by his remarkable self-discipline, a tide that fuels him now as he races ahead of her, somehow needing no navigational assistance as he picks his way unerringly towards the ship.

They've reached the docks now, and the Sunny is in sight. He skids to a stop, and hands her the cook's limp body. She's not surprised. His first priority is Sanji's life, but since he can trust her with that, trust Chopper to do all he can for the gravely injured man, his mind is free to fixate on what only he can do. Killing. Revenge. Making sure Gobei will regret ever laying a finger on Sanji. Making sure he'll never harm a single one of his nakama again.

"But if Luffy finds out..." she tries again.

"Sanji got beaten up by some women thugs." He locks gazes with her, making sure she gets the hidden message. Luffy mustn't know. He can't know that his mercy caused his nakama to get this hurt, that his judgment was for once wrong and that Gobei had no intention from the very beginning of keeping his promise to turn over a new leaf.

She looks down at the peaceful face with its curly eyebrow, and knows that Sanji would agree. He's the one who demanded silence from the Rolling Pirates about Zoro's sacrifice, after all. He would want to preserve Luffy's innocence just as much as Zoro does.

Something compels her to offer, "I can do it."

The response comes swift and sure. "No. Not you." He can see the anger in her own eyes, knows that even without it, she can easily deal with Gobei. But she's not an assassin anymore, she's an archaeologist, a preserver of knowledge. He's not going to let her return to the habits of the wretched past life Luffy rescued her from.

Not her, and not anyone else. Chopper saves lives, Usopp and Franky create their inventions, Nami her maps, Sanji his meals, Luffy smiles and new hope. They're creators, preservers - he won't let them be tainted by death. Brook has been touched by it, obviously, but he's no purveyor of death. Zoro's the destroyer, the one who visits destruction on the Strawhats' enemies. He's the one who will bear that sin.

"Are you sure about this?" she asks again, knowing how much trust he puts in Luffy, how much he's violating the trust Luffy puts in him.

He's silent for a moment, then he speaks. "You and I both know there are some people who can't be saved."

The skin at the back of her neck prickles when she realises it may not be Gobei he's talking about, after all.

He turns to go, and she reaches out for him, wanting to tell him that he's as much a preserver of life as Chopper, as much a preserver of smiles as Luffy, but he slips through the fingers of the last in her chain of hands and disappears, a vengeful spirit dissolving into the dark night.