A/N: The character pics will be in paragraph comments.
***
Sometime earlier.
A gray snake with a white underbelly slithered across the white dunes of Hueco Mundo. The three pink dots on either side of her head and the three pearls hanging from her white oyster-like mask all but confirmed her gender.
Walking by this snake Hollow was a fierce lioness with pieces of white armor on her four legs. What set this lioness apart was her golden mask and a golden mane extending beyond it.
Both Adjuchas females followed the lead of a golden-haired woman relatively small compared to her companions.
A light blue layer of skin-tight suit covered her from neck to bottom, nearly merging with her healthy bronze skin. A white, bone-like armor covered most of her body, with gills on her limbs and ribs. Sharp spikes protruded from her shoulders like pauldrons to an armor. A long tail extended from the back of her head; the tail had a shark-like fin in the middle and two joint fins at its end.
A giant white broadsword, like an elongated shark fang, was fused with her arm.
She was a powerful Vasto Lorde.
"Ara, Mila Rose, walk in front of us. We might lose sight of little you in this darkness."
"Gah, this snake bitch. Why is she so damn tall?"
The snake and the lioness started arguing. As always, it ended with the snake rearing up and hissing and the lioness crouching low and roaring. The two had a face-off like they were arch-rivals, despite being part of the same ground.
Tier Harribel shook her head. Sitting in a cave wasn't the most exciting thing in the world, so she and her two comrades went out for strolls in the white ashes desert. It usually ended with her stumbling upon ruins from the ancient era inhabited by Hollows, finding fascinating caves, and sometimes finding people she could trust like Franceska Mila Rose and Cyan Sung-Sun.
This sense of discovery on the horizon kept Harribel pushing every day.
Today, too, they had come out for a stroll, but her companions wouldn't stop fighting. She would let them sort this out and only step in when things got really messy.
Cyan Sung-Sun, the snake Hollow, paused her meaningless fight when she saw Harribel quietly staring in a direction. Harribel had a habit of calmly observing the situation first, revealing her thoughts second. The slight raise of Harribel's left brow was a sign things would go south as it was a sign of dangers that couldn't be sensed by their Adjuchas-level perception.
"Harribel-sama?"
Franceska Mila Rose also picked up the shift in Harribel's demeanor. "Hah! Harribel-sama, what has you looking so grim?"
"I sensed a strong Reiatsu." Harribel stopped in her path and blocked her comrades with her sword-like arm. Her golden brows knitted in a concerned frown. "A battle, perhaps."
"It doesn't concern us," said the lioness. "Leave it be, no?"
Mila Rose's tone embodied her matter-of-course, indifference to other Hollows' lives. Harribel had brought her and Sung-Sun together to protect each other, even if Harribel did most of the heavy work. Intervening in others' battles didn't sit well with Mila Rose as there was no point to trying to be a savior.
"We'll observe from a distance," Harribel addressed Mila Rose. "Follow me."
The cool and composed Vasto Lorde made a quick decision and charged ahead without waiting for her comrades' response.
Sung-Sun hissed. "Harribel-sama has more compassion for lives than both of us. It's about time we accept it."
Harribel always forgave the Hollows who tried to attack them, and she had spoken of her distaste for killing. She still killed the most pesky one every once in a while to let Sung-Sun and Mila Rose maintain their current Adjuchas status.
But she didn't help them devour Hollows to evolve further.
Sung-Sun and Mila Rose still respected Harribel for two reasons: Harribel had saved their lives and she possessed the power to act on her whims. Harribel could roam Hueco Mundo with confidence as no one would bother a Vasto Lorde unless they wanted to die. Everywhere, well, except for King Barragan's court.
Mila Rose scratched the ground with her paw and leaped a great distance. "Don't talk to me like I'm ignorant. I know Harribel-sama's contempt for sacrificing others."
"But you are impulsive, like a child." Sung-Sun giggled. "Harribel-sama, wait for us!"
"I'll kill you, bitch!"
The fierce lioness chased her snake comrade through the white desert.
***
Harribel soon found the source of the extremely thick Reiatsu—a Hollow, roughly the same height as hers, facing a giant Adjuchas. His Reiatsu was stronger than her, though not by much. Still, it was quite rare for her to come across such a powerful Hollow outside Las Noches's boundaries.
Harribel glanced at her frozen comrades, who were gripped by the primal fear of facing a being far above their strength. They showed a similar reaction when she had saved them from Hollows trying to devour them.
"He is a Vast Lorde."
This was the second Vasto Lorde Harribel encountered in Hueco Mundo, the first being the ever so disgusting Ruler of Hueco Mundo. That happened a few years ago. Now he'd have grown even stronger.
"Harribel-sama…" Sung-Sun took a gulp, the Hollow's Reiatsu continuously making her shiver despite their great distance. "We should leave before he notices us."
Mila Rose stomped the ground. "Argh, another man. He is gonna come after us. Let's ambush him while he is fighting the other Hollow."
She regained her violent bearing once she adjusted to the pressure and her proposal was a stark contrast to Sung-Sun's peaceful approach. She didn't want to leave any chance for the Hollow to ambush them later. Of course, that suggestion was made with the thought that Harribel's strength surpassed the other Vasto Lorde.
"Ara?" Sung-Sun looked at Mila Rose in confusion. "That Hollow has long hair and their face is concealed. How do you know their gender?"
Mila Rose stopped momentarily, then scratched her head with her paw. "I don't know. I just had a feeling… Gah, look at his figure. If that's not a man, I don't know who is!"
Sung-Sun blinked her eyes. Mila Rose might be onto something, as a Hollow's instincts were like a beast. "Harribel-sama, I'd advise against engaging in a fight. We might draw more enemies to us."
She took on a composed and serious demeanor, contrary to her earlier playful interactions with Mila Rose. That was just her messing around for a moment of entertainment.
Harribel nodded and continued observing the battle. She wasn't at all surprised when the unknown Vasto Lorde annihilated the Adjuchas with a Cero Ray.
"W-What? He killed an Adjuchas in one attack?!
Mila Rose stopped taking his prowess lightly. She had seen Harribel cut down Adjuchas like nothing. Fighting another Hollow on the same level as Harribel gave her quite the fright.
"I told you, Mila Rose," Sung-Sun whispered. "We can't fight him willy-nilly. It's best we leave right now."
Sung-Sun nudged Mila Rose's mane with her head before slithering away. Mila Rose quite agreed with Sung-Sun this time, so she followed after her.
Harribel wasn't so keen on leaving immediately. She stayed around, which allowed her to see the Vasto Lorde stretching his hand out to his companion, a familiar deer-like Adjuchas.
Harribel had a few encounters with Apacci in the past. From Harribel's distant observations, Apacci minded her own business and never went out of her way to attack others.
This led to Harribel marking Apacci as a friend of sorts. She would've gone out of her way to help Apacci.
'I'm relieved she found someone reliable.'
Harribel gave another glance at the male Vasto Lorde, who had his back turned against her, showing off his dark wings. Being Apacci's companion meant he wasn't like other Hollows in Hueco Mundo—devouring others wasn't his goal. Besides, devouring other souls wasn't optimal at their current level, as Gillian souls provided little to no improvements to their strength. Only Adjuchas did.
Sharpening their innate abilities and gathering comrades was more than enough to survive in Hueco Mundo.
She craved more strength but she never wanted it at the cost of other Hollows.
The male Vasto Lorde suddenly turned in her direction. Despite their distance, she could feel his eyes inspecting her from top to bottom.
Harribel retracted her gaze and shook her head.
'There is no point in staying here.'
***
Hollows didn't dream.
Their mind merely cycled through the memories of their soul—their most dominant soul, to be precise.
The fabricated phantasms could also be called an artificial dream.
In her false dreams, Harribel regularly witnessed a blurry white room, where metal screeched and sparked and blinding lights flickered everywhere.
Figures with white heads incited panic in their hypnotizing whispers.
Then an innocent cry rumbled through, shattering the reality itself until a void remained.
Waves and waves of an infant's sobs chipped away at Harribel's soul, carving out her innards and crushing her heart. A pair of white eyes welled up with moisture and oozed a trail of crimson tears until the chilling red painted her vision.
Harribel could instinctively feel the suffering behind each tear.
At that precise moment, she opened her eyes on a slope, with her hand on her left knee and her right knee folded. She showed no signs of discomfort, as though she forgot every experience inside her false dream.
That was precisely the case. Her oozing sympathy and regret had receded back into her soul after she woke up. She could never truly recall the experience of her past life—the experience she once had as a mother.
Harribel suddenly raised her head. Shrill screams echoed through the dreadful vistas of Hueco Mundo. It felt as though they came from far away, carried by the distant hills.
Grains of ash-white sands moved in waves as Mila Rose and Sung-Sun woke up from their brief slumber.
"Sung Bitch, did you hear that?"
"Ara, don't be vulgar. And yes, I did. Someone probably ticked off a pack of Menos Grande."
"Could it be that male Hollow?" Mila Rose's mind immediately went to the terrifying Hollow they encountered. "S-Should we leave?"
"Why would he disturb Menos Grande? The world doesn't revolve around him." Sung-Sun squinted her eyes. "Why do you keep bringing him up? Did you, by any chance, get a crush on him?"
Mila Rose was always a worshiper of strength, her past playing a big role to make her envy the strong. It wouldn't be far-fetched to think Mila Rose would catch feelings for a much stronger Hollow.
"Stop talking gibberish." Mila Rose turned her head with a harrumph. "I just thought he'd be linked to this incident. He seemed like the troublesome type."
"You certainly know him more than us."
Harribel closed her eyes. Her companions hearing the howls revealed a glaring detail—the conflict was closer this time around. She also sensed Apacci's Reiatsu flaring up alongside her winged companion's.
'They can take care of each other.'
She ignored the howls and hung her head for another session of light sleep, as if subconscious yearned to relive the nightmare again and again.
***
Just a few minutes later, Harribel woke back up with a jolt. A spine-chilling wail reverberated as an intense Reiatsu declared its position, rising with each moment.
The pressure was so thick it nearly choked her Adjuchas comrades. Then the pressure disappeared entirely, leaving her party in a state of confusion.
Harribel glanced at her friends. "Head back to the base. I'll go check it out."
Before Sung-Sun and Mila said a word, Harribel leaped into the air and dashed. A boom resounded as Harribel reappeared several feet away. A series of successive sonic bursts rumbled as she made a quick dash for the origin of excruciating howls.
Another shriek came and died before she reached her destination. What she saw left her petrified.
A giant bird-like Hollow screeched as he tried to cover his face with his wings. Dark Reiatsu overflowed from his entire being and pushed the ash sand around him. His Reiatsu surpassed the limits of an Adjuchas, faintly touching upon the realm of Vasto Lorde.
His Reiatsu rampaged more before slowly receding into his soul. Vasto Lorde… Adjuchas… Gillian. His Reiatsu sank rapidly then disappeared entirely. The Hollow collapsed to his knees and a gust of wind scattered his husk of a body into ashes.
***
A/N: Since most of their backstories are unknown, I have taken the liberty to change some things. One of them is Harribel being a mother who died during childbirth, essentially going through childbirth despite knowing the risks to her own life. The story meshes too well with her Aspect of Death Sacrifice and her Hollow hole positioned in her womb.