Kai's method of absorbing souls was a delicate operation, akin to the care one would take in filling an already brimming bucket with water. The bucket, symbolizing Kai's body and spirit, was full to the top with his own essence, the water representing his soul. As he prepared to integrate another soul, he approached the task with the meticulous care of a master craftsman. He sought to increase the capacity of his 'bucket', to enhance his being to encompass more without spilling a single drop of himself. The souls he chose to absorb were not just random spirits; they were carefully selected, each carrying a weight of significance that could bolster his power or knowledge.

This process was not without its risks. If Kai was not precise, if he allowed too much 'water'—the essence of another—into his bucket, his own 'water' might be forced out, spilling away. That could mean losing a part of himself, his individuality, his memories—turning into a shell occupied by another's will. He couldn't afford such a loss. Each soul he chose to weave into his being was an exercise in control, in expanding his own limits without losing the core of who he was.

The filtering of what each soul carried was another part of the task that required finesse. Like sifting through sand for gems, Kai needed to distinguish useful knowledge and power from that which was redundant or unnecessary. This was not just a matter of space within the 'bucket', but of maintaining the purity of his essence. The essence of souls was vast, filled with experiences, emotions, and memories—too much for any vessel to hold completely. Discernment was crucial, ensuring that what he absorbed would not bring him to the brink, would not overwhelm or contaminate his own spirit.

As he stood facing the soul of the Soul King, he knew he was approaching a task unlike any other he had undertaken. This soul was a beacon of faint light, seemingly inconsequential among the others yet its inherent significance was unparalleled. Kai focused, preparing himself for an integration that would require him to push his limits, to expand the capacity of his 'bucket' further than ever before, while still preserving the integrity of his own 'water'.

The delicate dance of expansion and integration was a silent symphony played out within the recesses of Kai's being. It was an internal struggle unseen by others, a battle of wills between the soul he was absorbing and his own, a testament to his mastery and a glimpse into the enigmatic nature of his power.

Taking a deep breath to steady his focus, Kai reached toward the faint light within his mindscape, the essence of the Soul King. The touch was a mere brush, a whisper against the ethereal glow, yet it initiated a cascade within him. The "water" of the soul began to fill him, a slow trickle at first, a current of pure power seeping into his being. He had to expand his soul's capacity, to make room for this new influx, a task that demanded every ounce of his will.

The process was far from easy. Pain flared through him, a signal that he was pressing against his own limits. Kai's face contorted in concentration, the skin above his brows creasing as he focused on the task. It was a battle of wills, his against the overwhelming surge of the Soul King's essence. Each second was a painstaking effort, like climbing a mountain with no end in sight. His breath came in sharp bursts, evidence of the strain he was under.

As the "water" filled him, it threatened to overflow, to overwhelm his senses and wash away his identity. Kai had to be precise, directing the flow into the crevices of his spirit that could contain the power without bursting. It was a balancing act, a masterful display of control over his own domain.

His body, though stationary, seemed to be on the verge of shuddering apart, every muscle tensed to its limit. The integration of the Soul King's essence was a careful threading of the finest needle, each thread of soulful "water" guided into place with meticulous attention. Kai's consciousness hovered between the physical realm and the deep recesses of his mindscape, where the soulful light began to settle, finding a new home within him.

The pain and effort etched deeper lines into his normally passive features. His usual laziness was nowhere to be found in these moments of intense focus. He couldn't afford a single slip, a moment's lapse in concentration. The stakes were too high, and the potential for disaster too great.

Kai's mental fortitude was the only barrier against the tide that threatened to sweep away everything he was. With immense willpower, he drew the power in, weaving it through the fabric of his soul. It felt like an eternity passed in the span of minutes, his very existence hanging on the edge of a knife.

Memories started to fill Kai, so vast and endless he felt as if he was living billions of lives at the same time. His own memories, like a flicker of match fire encountering a blizzard, were threatened to be extinguished. No matter how powerful his soul was, his life accounted for just 18 years; his experiences were rich yet limited in the face of eternity.

Kai experienced life after life in a dizzying rush: a mother's first touch, a warrior's last stand, the warmth of sun on an ancient earth. He saw worlds spinning into creation, heard the very first laugh, tasted the first rain. This was the memory of the Soul King, a consciousness that spanned the ages, a whisper in the heart of every living thing.

But amidst this flood, he fought to keep his own essence alive. He clung to the sparks that made him Kai — the first time he found his power, the weight of a sword in his hand, the sting of betrayal, the rush of battle. Each precious memory was a lifeline back to himself.

The sensations came in waves, each carrying the weight of eons. There were visions of ancient wars, the rise and fall of empires hidden in the fabric of time. He saw the birth of stars, the creation of worlds. Each memory was a life he hadn't lived, a piece of a puzzle he had never seen before. It was overwhelming, threatening to drown him in a sea of endless pasts.