At The Peak of One Piece

Victor and Rebecca returned home. Lunch wasn't ready yet, so Victor pulled two large chunks of Zebra Donkey meat from his pack. He prepared three dishes right there, eager for them to taste this delicacy. Rebecca busied herself outside processing the giant boar carcass – keeping some parts, preparing others to give away.

Once Toya finished her cooking and Victor's dishes were ready, Rebecca helped carry everything to the table. The four of them sat down to eat.

"Quick, try these dishes I made," Victor urged with a smile. "This is the best meat I've ever tasted. I brought it back specifically for you. Go on, taste it."

"Alright, alright," Grandma Maria chuckled, amused by Victor's enthusiasm. She picked up a piece of braised meat – perfect for her aging teeth. She placed it in her mouth, chewed a few times... and her expression transformed. Tenderness, juiciness, an explosion of flavor. She savored it, reluctant to swallow, a look of pure bliss on her face.

Seeing Grandma's reaction, Rebecca and Toya eagerly scooped up meat. Their faces mirrored the same wonder after tasting it.

"I've never eaten anything so delicious! I feel... happy!" Toya sighed, hands pressed to her cheeks, utterly enchanted.

"Victor, where did you get this meat? Take me hunting there!" Rebecca demanded, wanting an endless supply.

"Don't even think about it," Victor laughed, deliberately provoking her. "You're not strong enough yet. Go train harder, little girl."

"This meat... Grandma should eat more of it. It's good for her health," Victor said, addressing Rebecca and Toya. "I'll leave a good portion behind for you to prepare for her."

"Victor... are you leaving again?" Grandma Maria's warm smile faded, replaced by a hint of sadness. Rebecca also looked at him, disappointment clear in her eyes.

"Yes, Grandma," Victor replied, his expression turning serious. "My training isn't complete. This was just a short visit. I'll need to leave again in a few days."

"But don't worry," he added quickly. "Captain Buck sails this route regularly. If anything happens, send word with him. I'll come back fast."

"Enough of that now," Grandma Maria said, forcing a smile that didn't quite reach her eyes. "Victor's training is important. Everyone, eat this wonderful food before it gets cold."

The meal continued with less chatter. Conversation mainly consisted of Grandma Maria asking Victor about his life away from the island.

After lunch, Victor insisted Grandma Maria rest in bed. He then took Rebecca to the forest. There, he meticulously explained his understanding of swordsmanship and Observation Haki – concepts like the "belief that cuts steel" and "will controlling Haki." How much she grasped depended on her own insight. He also briefly mentioned the Rokushiki techniques but advised her firmly not to attempt them yet; there would be time later.

In the evening, Old Man Buck arrived. Victor prepared a feast and bought several bottles of good wine, sharing drinks with the old captain. Buck urged Victor to join the Marines. Victor replied it was still early; he had more to learn first, but he would join eventually. Pleased, Buck drank a few extra cups, needing Victor's help getting home later. After returning, Victor wrote down the training methods he'd explained to Rebecca, worried she might forget crucial details once he was gone.

Three days passed swiftly. Victor spent them focused on training with Rebecca – his main purpose for returning was to show her the path forward.

During their sparring sessions, Victor constantly guided Rebecca, feeding her moves and steering her development. The results were noticeable; at the very least, her movements became less flashy and more purposeful.

Victor handed Rebecca the training manual. He instructed her to prepare the meat he'd left behind slowly for Grandma Maria, emphasizing its health benefits.

Mayor Andre visited once during this time. He'd heard astonishing tales of Victor running on the sea and flying through the air. Learning Victor was leaving again soon, he left with a palpable sense of disappointment.

The three days passed in a blink. When Victor departed the island, his pack now half-empty, only the grandmother-granddaughter duo and Old Man Ba came to see him off. 

... 

At sea, Victor continued his training regimen. But he soon noticed something intriguing: frequent use of Observation Haki led to gradual improvement. 

This was only perceptible due to his absurdly heightened physical senses. For most people, the incremental growth of Haki was too subtle to detect—but Victor's body registered even the slightest enhancement. 

That said, "growth" was relative. He wasn't about to become invincible overnight. His progress was simply faster and more noticeable than the average person's, compounded by his acute self-awareness. 

So, he began a new routine: keep Observation Haki active until depleted, recover, repeat. 

Through trial and error, he confirmed that each cycle strengthened his Haki by a hair's breadth. He wasn't sure if this was unique to his physiology or a universal truth. 

Another discovery: eating Essence-rich meat after exhausting Haki drastically sped up recovery. 

This led him to two theories: 

1. Observation Haki "waves" absorb ambient Life Essence when active, amplifying their potency over time. 

2. Consuming spirit-rich food replenishes this energy, accelerating both recovery and growth. 

"So the world's energy fundamentally ties to Life Essence." 

Extending this logic, he speculated on how Armament and Conqueror's Haki might similarly evolve—though without awakening them yet, it remained academic. Still, the importance of Life Essence was undeniable. 

 Wild Speculation Time: 

Fujitora's Case: 

- His blindness forced him to permanently rely on Observation Haki, refining it to cosmic levels (hence sensing meteors in orbit). 

- Gravity manipulation? Just yank them down via Haki-locked coordinates. 

Katakuri's Case: 

- Pre-Mochi Fruit, he couldn't secretly eat donuts without Haki alerting him to intruders. 

- Post-Fruit, Big Mom's volatility made constant Haki vigilance mandatory (lest a sibling get purged). 

- Result? Future Sight emerged from sheer survival necessity. 

"Most people never grasp this 'Haki growth hack.' Only a few stumble into it accidentally. Heh. Jackpot." 

Thus, the training maniac added a new rule: Observation Haki stays ON until empty. 

Small Sea Kings in the East Blue soon faced genocide. Every detected blip on his Haki radar became spirit-infused meat for recovery. 

"Fewer Sea Kings mean safer seas for fishermen and ships. Really, I'm doing charity work here."