I was just thinking about the time when a lot of people thought Zoro had lost his arm over the timeskip. I saw someone somewhere saying that maybe he'd learned to use Armament Haki to sort of replace the lost arm in order to keep his three-sword-style, so… this happened.
Stronger
Luffy drank in the sight of his crew, his nakama, finally. He'd missed them like a physical pain, an ache that had plagued him for two years and was only fading now.
He threw himself at his first mate, standing closest. He wrapped his arms, impossibly tightly, around Zoro, feeling the sturdy warmth of his broad chest.
"Good to see you too, Sencho," Zoro said, wrapping a single strong arm around Luffy's shoulders. A single arm… Luffy pulled away from Zoro, feeling like something was suddenly blocking his throat. He frantically pulled at the sleeves of Zoro's robe, exposing his shoulders. Luffy's fingers dug into Zoro's left shoulder, into the flesh just above the naked stump that was once a powerful arm.
"What…"
Zoro didn't answer, didn't flinch. Luffy pulled away from his first mate sharply. Pulled back his arm and punched Zoro as hard as he could.
Zoro went flying, crashed into Sunny's side. Franky growled in anger, standing on the deck with the rest of the crew who were silently watching the exchange between captain and mate.
"I told you to get stronger!" Luffy roared, eyes alarmingly dark beneath the brim of his hat. "You're supposed to become the world's greatest swordsman! Not weak!"
"I have become stronger," Zoro answered calmly, wiping the blood from his nose as he rose to his feet.
"Armament haki." Zoro's voice remained low, even, and his eyes remained on Luffy's tense form. A shape like a ghostly black arm replaced the emptiness on Zoro's left side. Calmly, he unsheathed his three swords, one gripped by the black hand.
And then, without warning, he threw himself at his captain. Luffy reacted without hesitation, meeting Zoro's swords with his own haki-enhanced limbs. He pinned Zoro easily, hands digging into his shoulders, hat pulled down low over his eyes.
Tears dripped down onto Zoro's face, and his tense body relaxed under his captain's hands.
"Just like Shanks," Luffy said. "You're so stupid."
Zoro laughed, freed his arm to reach up and push Luffy's hat away from his eyes.
"Look who's talking."
Luffy collapsed onto Zoro's chest and wound his rubbery arms around his crewmate.
"I'm glad you're alive."