(A/N: For this story, Taichi and Hikari are not biological siblings. Please understand.)
In the Digital World, Taichi stared at the screen, momentarily stunned by Hikari's heart-wrenching cries.
'These words...'
'Were these Hikari's true feelings, hidden in her heart all these years?'
Memories surfaced in his mind like scenes from a film.
Age three.
His parents brought a timid little girl before him.
'Taichi, from now on, she is your little sister. Her name is Yagami Hikari. As her big brother, you must protect her.'
Little Hikari hid behind their mother's leg, looking up at Taichi with shy, nervous eyes.
'Okay. I will definitely protect my little sister.'
Little Taichi clenched his fists, the brave, determined light in his eyes seeming to respond to the little girl's timid gaze.
He was the big brother.
Hikari's eternal big brother.
A bond of kinship, deeper than blood, was forged between them.
Ten years ago, during their adventure in the Digital World, Taichi would never forget the moment he flew into the sky, with Hikari clutching the hem of his clothes.
That look in her eyes... In little Hikari's eyes, the entire world was less important than Taichi alone.
Later, after returning to their normal lives, Taichi came to realize that he and Hikari couldn't live together forever.
'Hikari will fall in love someday. Onii-chan will marry Sora. We'll have to part ways eventually.'
'No! Hikari wants to always be Onii-chan's little sister! I want to keep acting spoiled with Onii-chan!'
Little Hikari hugged Taichi's leg, her little face flushed.
Back then, Taichi thought Hikari was just young and didn't understand.
He never expected... 'Her true feelings were to be her brother's little sister for her whole life.'
Taichi watched Hikari's tear-streaked face on the screen, his heart trembling violently.
He had always thought Hikari would get married someday, would become someone else's bride. So he had always played the role of the gentle big brother, smiling and comforting Hikari.
But now, hearing his sister's true feelings poured out, even the heart of the darkened overlord Taichi beat strongly.
The cute way she looked learning to talk...
Every moment of her growing up, becoming a graceful young woman...
He didn't want to share her with anyone else.
He didn't want Takeru, the brother of the betrayer, to take her away.
His little sister would always be his little sister!
"Agumon! I can't wait any longer! Is there a way to transmit the Crest Kurai prepared to Hikari? I can't stand watching her be possessed by that thing, Homeostasis!" Taichi clenched his fists, shouting to Agumon beside him.
He hadn't prepared Crests just for Koshiro. If the darkened form of Knowledge was turning the grand wish to share with everyone into a dominion held by oneself alone... then the darkened form of Light was turning the light that brings hope to the world in an instant into something hidden deep within the soul, existing for only one person…
Heart.
The power of the Heart was far stronger than external light or saintly salvation.
"Sigh. It's possible, but Hikari is currently under Homeostasis's surveillance. Are you sure you've considered the consequences of doing this?" Agumon adjusted his goggles, his expression resigned.
He knew this was just Taichi's nature. Even after his darkening, he couldn't suppress his protective instincts towards the people and things he cherished.
"Of course. Even if my own preparations aren't enough, as a last resort, the Group Owner has my back." A slight smile touched Taichi's face, which had been perpetually cold since his darkening, revealing a trace of relief.
"You, you... I really don't know why that mysterious and powerful Group Owner is so good to you. Fine, I'll send the Crest program over." Agumon shook his head in mock exasperation, his claws beginning to fly across the virtual keyboard.
Whoosh…
With Agumon's actions, a wisp of a Crest program, shimmering with a faint light, passed through a pre-prepared Digital Gate, accurately targeting New York.
"Koshiro, prepare a holographic projection. I need to speak to Hikari myself." The moment the Crest was sent, Taichi spoke softly to Koshiro far across the Pacific.
"Understood. According to model analysis, your safety rate for this operation is 87.81%. I will do my utmost to protect you." Koshiro nodded, a serious look appearing on his calm, rational face.
What followed would be a fierce contest between him and Homeostasis.
Whirrrrrr…
Countless precise data storms swirled around Koshiro, forming layer upon layer of data models. As a nascent form of Yggdrasil, he naturally knew some methods to temporarily block Homeostasis.
However, the time was extremely brief, likely less than a minute.
Click.
Koshiro pressed a key. The countless data models unified, forming a phantom resembling a clock.
"Taichi, now! Quick! We only have one minute and thirty-two seconds!" Koshiro shouted to Taichi on the other end of the screen. The clock behind him began its slow countdown, emitting a steady tick-tock.
"Good. Thanks." Taichi shot Koshiro a grateful look. His body distorted, and his projection rapidly descended upon New York City.
…
Fizzle…
Back in the present.
Just as Hikari's voice grew hoarse from crying and BlackWarGreymon stood stunned, a distorted white light tore through the barriers of space and dimension, appearing before them.
Seeing that familiar figure, both BlackWarGreymon and Hikari's pupils contracted sharply, exclaiming in unison.
"Taichi / Onii-chan!"
Hikari rushed forward to embrace him without a second thought, only to pass right through Taichi's holographic projection and fall heavily to the ground.
"Onii-chan?!" Hikari looked up at Taichi, tears welling in her eyes, her expression full of sorrow and confusion. She thought she couldn't hold him because he was still angry with her.
"Ah, there's no time to explain the details now. The main point is, Hikari, I heard everything you just said. I want to tell you that I never blamed you from the start! It was all that guy BlackWarGreymon interpreting things on his own!"
With that, he shot a slightly angry glance at BlackWarGreymon and continued, "I only have one minute and thirty-two seconds. I need to explain this to you quickly."
"Right now, Agumon, BlackWarGreymon, and I are building an empire in the Digital World. We desperately need capable allies. A powerful and mysterious being gave us several Crest programs, similar to the ones from before but infinitely more powerful. Accepting the inheritance of this Crest program can make you unimaginably strong. But the cost is... you must become an enemy of the world we once saved. You must abandon everything and stand by my side."
Taichi took a deep breath, looking solemnly at Hikari.
"I don't want you to feel any pressure. Even if you don't accept, I will still…"
"I accept." Hikari nodded rapidly, not a hint of hesitation on her face, "I was wrong once before. This time, even if it means making an enemy of the whole world... even if you were to take a knife and slice my flesh inch by inch... I would never let go!"
Her bright, determined eyes gazed deeply at Taichi.
She was Taichi's light. Even if she used up the last shred of her energy, she would illuminate the path forward for Taichi.