Crocus stared at Nami in shock.
"How the hell did you do that?"
"I just... felt it. The wind over there wasn't right."
Crocus shook his head in wonder. "Your talent for reading weather patterns is extraordinary. With a navigator like you, this journey should be much smoother than most. After all, on the Grand Line, the greatest danger isn't always the enemy, it's the weather itself. One careless moment and you might get swept into a hurricane, or dragged down by a massive whirlpool, and that's the end of your story."
"Don't say such terrifying things," Nami complained, shooting him an irritated look.
Crocus just smiled and shrugged. "This sea is what it is, dangerous as hell. About forty percent of all pirates and merchant ships that enter the Grand Line just... disappear. No trace. The ocean swallows them whole."
His attention then shifted to Marcus, and his expression grew thoughtful.
"Your vitality is overwhelming. It's like there's a furnace burning inside you, constantly generating energy."
Marcus was puzzled. He knew his body had changed since eating the Devil Fruit, but he'd always assumed it was just the Minecraft mechanics, when his hunger bar was full, he never felt tired or exhausted.
But clearly, this was something different.
"I think I know what's happening..." he said slowly.
He'd always wondered where the excess food went when he ate beyond his maximum hunger and saturation levels. Did it just vanish into thin air, or was there some invisible storage system his body used?
Now he understood, all that overflow hadn't disappeared. It had been converted and stored in his body in another form.
He could feel it coursing through him, this incredible power just waiting to be used.
Focusing his mind, he concentrated that energy into his left hand and threw a punch forward.
CRACK!
The air itself shattered with a sonic boom.
His eyes lit up at the success. The next instant, he vanished from where he stood.
Nami blinked in confusion, looking around frantically.
But Crocus was already looking up at the sky, where Marcus was now soaring more than thirty feet above the ground.
BANG!
Marcus stepped on the air itself, creating a visible shockwave that rippled outward.
"Geppo?!" Crocus exclaimed. "How the hell does a rookie know one of the Rokushiki?"
They watched as Marcus continued climbing higher using the air-stepping technique, until he became just a speck against the clouds.
"He's... flying?!" Nami finally processed what she was seeing.
But less than a minute later, Marcus came plummeting back down, landing on the deck with a heavy thud.
"Damn, Geppo is more exhausting than I thought," he panted, wiping sweat from his forehead.
"How did you do that?" Nami demanded, and she wasn't the only one curious. The sound of Marcus' aerial acrobatics had woken the others, and soon Alvida and Kira were crowding around.
"It's... hard to explain," Marcus said, catching his breath. "I guess you could call it a form of Life Return. I concentrated all that stored energy into my hand."
CRACK!
Another air-shattering punch demonstrated his point.
"Like this, I hit the air hard enough to create an explosion, then ride the rebound force upward. But since you're in mid-air with no solid footing, chaining the movements together requires incredible technique and body control."
Marcus scratched his head sheepishly. "I kind of learned it backward, though. It's like learning to run before you can walk."
The explanation sparked interest from the rest of the crew. Soon, everyone was experimenting with trying to feel this mysterious energy, resulting in various awkward attempts and wild gestures.
Luffy and Kira had the easiest time since they already understood the basics of Life Return. The others could sense something stirring within them but couldn't figure out how to actually use it yet.
Kira benefited the most from the discovery, significantly boosting her transformation abilities and making her shifting between forms smoother and more efficient.
The downside for Marcus was that using these techniques burned through his stored energy incredibly fast. That night, he found himself extremely hungry again and ended up raiding the ship's fruit supplies.
Seeing him eat, Luffy's own appetite was triggered, and he joined the feast.
"Hey Luffy," Marcus said between bites, "you can feel the energy now, and you already know Life Return basics. That means you should be able to make that energy flow faster through your body, right?"
"Mmph? I think so," Luffy replied around a mouthful of apple.
"Want to try something?"
Under Marcus' guidance, Luffy began concentrating on the energy flowing through his body. Gradually, his skin started turning red, and thin wisps of steam began rising from his pores.
"Yeah, that's what I expected..."
He knew from the original story that Luffy would eventually develop Gear Second by using his rubber powers to squeeze his limbs like pumps, creating a second heart effect that sped up his metabolism. But the high temperatures and rapid blood flow came with the serious side effect of shortening his lifespan.
The principle was similar to how a high fever could cause brain damage, when human cells exceeded 40°C, they started taking permanent damage.
"This is exhausting... I can't maintain it and do anything else at the same time," Luffy complained, the strain showing on his face.
"Try using your rubber ability to help," Marcus suggested. "Compress your arms and legs to passively speed up your circulation instead of forcing it."
Luffy didn't overthink it, he just started experimenting with different ways to use his powers.
Soon, he successfully developed his own version of Gear Second, though it was different from what Marcus remembered from the anime.
"It works! And... holy crap, I feel so much faster!" Luffy grinned with excitement.
Marcus observed the results carefully. The steam coming off Luffy's body was much less than expected, and his skin only flushed slightly red, similar to the perfected Gear Second that Luffy would achieve after years of training in the original timeline, but with far less physical strain.
The difference clearly came from the contrast between active and passive control. Instead of forcing his body into overdrive, Luffy was working with his natural abilities and enhanced life force to achieve the same effect more efficiently.
Early Gear Second was almost uncontrollable and dangerous. But with proper guidance, Luffy had developed both his rubber powers in a much healthier way.
Of course, the end result was that Luffy's appetite increased even more than before.
Looking at the nearly empty fruit storage, Marcus sighed helplessly. It looked like he'd be spending even more time speed-growing crops and harvesting trees.
---
Time passed, and the next day arrived with preparations for departure.
To show gratitude for the notebook Crocus had shared, Marcus had crafted several storage chests, fishing rods, and even hollowed out a 30x30x4 meter space within the Red Line.
He'd offered to expand it further, but Crocus said there was no need, most of his time was spent inside Laboon's stomach anyway, so the extra space would just go unused.
Instead, Marcus focused on leaving behind plenty of fishing equipment and a great supply of fruits that would last for months.
As for modifying the iron ship-island, he only added a few observation platforms, no major structural changes were necessary.
"Alright, we're heading out!" Luffy shouted from the bow, waving energetically.
Laboon and Crocus watched them depart, the massive whale's gentle eyes following the ship as it sailed toward the horizon.
"He's such a good-hearted kid, Laboon," Crocus said, patting the whale's side.
"Uuun~" Laboon's deep voice rumbled in agreement.
"The seas are getting lively again. I wonder what kind of adventures they'll find out there."
---
Meanwhile, the Straw Hats were getting their first real taste of the Grand Line's infamous weather patterns.
One second the sun was blazing overhead, the next they were being pelted by hailstones the size of golf balls. Before they could even process that change, it had shifted into a full blizzard with temperatures plummeting below freezing.
The extreme weather swings were so rapid and dramatic that nobody knew whether to wear summer clothes or winter gear.
"This is exactly why each island on the Grand Line has such different climates," Vivi explained with a smile, watching the crew's reactions. "But this chaotic weather only happens in this stretch of sea. The magnetic fields from seven different islands overlap and interfere with each other here, creating these conditions. Once we get further in, the weather becomes stable."
Nami sighed, pulling her jacket tighter as snow began falling. "Just our luck to hit the weather chaos zone first thing."
On deck, the guys had already adapted to the situation by starting a snowball fight and building crude snowmen from the rapidly accumulating snow.
"These idiots... can't they take anything seriously?"
"Come on, I think it looks fun. Want to join them?" Vivi suggested.
Nami grumbled under her breath but followed her outside anyway.
"Incoming!" Luffy's voice rang out as warning.
The moment she stepped onto the deck, a snowball the size of her head smacked Nami in the face.
Luffy immediately realized his mistake and started shivering.
"Oh no... I'm dead."
"You guys are going to pay for this!" Nami declared, her smile far more dangerous than the blizzard around them as she began forming her own ammunition.
What followed was an epic snowball battle that lasted until the weather shifted again, this time to a gentle spring rain that melted their frozen battlefield and left everyone soaked but laughing.
Welcome to the Grand Line, indeed.