"What's this nonsense, Oto-san?!"
Even as Mori complained, he didn't react rashly.
After all, he wasn't lacking in intelligence and knew full well that Doma could end his life at this very moment.
The question was: why was this powerful demon asking him to die?
'Is it for his plan? No… why would he have bothered raising me all this time?'
Mori's mind was in turmoil.
The young man searched for logic in his father's casual words, as ever since their conversation began, Doma had proven utterly unfathomable to the duo.
The demon had been waging a battle against Muzan for decades, planning his moves years in advance.
Mori judged that his death must conceal something, even though Doma had spoken half-jokingly.
"Don't get mad, haha. I just need you to speed things up a bit with Lin or her daughter. You see, I'm a little worried about your sexual preferences and your bloodline," Doma explained honestly, after managing to calm Mori down.
"My bloodline? I don't understand. And why are you so interested in me and Lin?" he said in an irritated tone, having caught his father's insinuation about his possible homosexuality.
"Unfortunately, I can't tell you about your bloodline or your origins. Either way, you won't be around in a hundred years," Doma replied, without clarifying his little jab at Mori's supposed inclinations.
Doma simply shrugged, as if to say: 'that information isn't relevant to you.'
"The dead don't need to know much, and I just need a strong lineage from you, Mori-kun. So don't hesitate to take the mother and the daughter… no, become a harem king like Taiga-san."
The ice demon nodded after these words, as if pleased with the idea.
'The more children Mori has, the more I can observe the differences between him and the Ubuyashiki clan,' he thought, analyzing his son like an intriguing experiment.
The Ubuyashiki clan descended from Muzan Kibutsuji's lineage.
In the manga, their leader had a gift for predicting future events with minimal information.
Doma found that strange.
Especially since this family had evaded Muzan for centuries.
Even without Yoriichi and his breathing techniques, they had already engaged in the fight against their demonic ancestor and hadn't been wiped out quickly.
Doma didn't believe in such convenient luck, especially not luck that had persisted since the Heian era.
That was nearly a thousand years by now.
He still suspected interference, the kind that had hindered him back then from unlocking his demon slayer mark and still prevented him from finding the flower Muzan so desperately sought.
'Mori was born with a healthy body, since I tried to be as human as possible during his conception with Kaguya in our chamber, but…'
Doma knew it well.
Muzan's blood flowed through his veins, and thus through Mori's as well.
Biologically speaking, Muzan was technically his grandfather.
Yet the curse of the Ubuyashiki clan had not yet manifested in the boy.
However…
'Mori already has supernatural foresight, based on my observations.'
This was a problematic element, as pure manipulation wasn't a good idea against Mori.
Doma had to win him over to his cause through honesty, omitting certain inconvenient details, like the activities of his disciple Enmu.
Thus, Doma put a bit of pressure on Mori to have children before a possible death dictated by the will of the world itself.
"Uh… Doma-sama, can I also have a harem? I've noticed a servant who keeps looking at me, and I—"
Gyutaro wanted his share of the pie offered to Mori, but Doma immediately shut down his ideas.
"Forget it. That servant is a harlot who's toyed with nearly every non-ascetic man in the monastery. You'd just get devoured and cuckolded," he said in a tone filled with pity for Gyutaro.
The man was in his twenties, but like his rival Mori, he had no real romantic experience.
"I'm used to the Oreins, and—"
Once again, Doma cut off Gyutaro's strange ideas.
This time, not with words, but first with a fan strike to the head.
Bonko mode.
(Image)
"Stop being so hasty. You'll have plenty of time to find a woman when you become a demon," he said, after pulling the fan away from the young man's head.
"You want to turn Gyutaro into a demon?!"
To Mori's question, he received only a vague response.
"Of course. If you're to increase the sect's influence within the Demon Slayer Corps, then Gyutaro must act among the demons."
After these words, Doma turned his gaze back to Gyutaro.
"So? Are you interested? You'll have a long life, and you'll be able to love and do all the things you never had time for. Of course, you'll stay young forever, and you can share that with Ume."
Doma cut his palm and filled an empty water bottle with his blood.
"I won't pressure you, Gyutaro. After all… you already know the darkness of this world, unlike Mori."
Doma didn't continue the conversation and left the scene, after taking Gyutaro to a room where he set up several mental defenses in his mind.
He already knew Muzan wasn't watching anymore, but if Gyutaro chose to drink his blood, Muzan could access that conversation.
"Oto-san! You're not offering "me" to become a demon?!"
Mori stared at Doma's back with a mix of complex emotions.
But the strongest were frustration… and reluctance.
Now, he understood a bit why he was going to die after the scene with Gyutaro.
He was just a mere human.
No matter his indomitable spirit or intelligence, time would erode and erase everything.
To Doma, he was but a drop of water in the endless river of his potential eternity.
How could he not see Mori as already dead?
"I told you, didn't I? You need to have a lineage. Don't you want to live on through your children? Pass down your will? But there's indeed another reason behind my reluctance to offer you that path."
Doma glanced over his shoulder.
"I don't want another "me"… you have to be better."
Doma gave a fake smile, but he felt those were the right words to say now.
After all, he wasn't going to tell Mori he wanted to experiment on his lineage and uncover the limits of the foresight of Muzan's human descendants.
Tear.
Doma hadn't noticed, but he had never spoken such strong words to Mori before.
When Mori established a branch of the sect in another city, he received only words like: ´great, amazing, as expected of you,' and other similar phrases.
Doma had never expressed genuine pride through his words or strong encouragement that could be interpreted as recognition.
There was also the fact that Mori had always felt a wall between him and his father.
Now, he could no longer perceive it.
Doma was no longer keeping that distance with his son, having revealed a good portion of his secrets.
That's what Mori felt when he no longer sensed the invisible wall between him and Doma.
There was no longer a great distance between them.
His father stood before him, smiling.
'F-Father, I… I just wanted…'
Unfortunately, the words never left Mori's mouth that day.
Doma also no longer had the mental strength to read others' minds or manage his vector power.
The father would never know his first son's true intentions, and the latter no longer knew what to think of the once-arrogant boy.
Was it really just an experiment? A scheme to preserve his sect without losing it? An action driven by his desire for Kaguya's delicate body back then?
Doma could no longer answer those questions precisely.
His rational mind had already made him understand that only eternity was worth pursuing in this world.
Yet…
'I've loved, I've had friends, I've fought, I've been hated, I've been adored, I've helped, I've betrayed, I've manipulated, I've deceived, I've conquered, I've been enslaved, I've enslaved in turn, I've stolen, I've been stolen from, I've given, I've…'
At that moment, all his actions since his reincarnation in this body flashed through his mind after parting with a tearful Mori.
Doma rationally contemplated all his actions.
In the end, he gave himself a rational judgment devoid of any emotion.
"Yes, Muzan… we are both selfish monsters, and we have a guaranteed place in hell."
The demon let out a sigh whose true meaning no one could decipher.
"Eternity… yes, it's the only path left to us. Otherwise, we couldn't hope to achieve our true goal."
He said this as the sun set on the horizon.
Before Doma, the sky took on a scarlet hue, as if heralding the future bloodshed his choices would bring.
'Yes, we must give true meaning to all these deaths we've left in our wake.'
…
Ten years later, the young sect leader fell ill with an unknown disease.
No doctor could cure him, and the head of the Ubuyashiki clan considered the Ogai clan as kin, having recognized the symptoms of Mori's illness.
Unfortunately for the Demon Slayer Corps and the sect, the Flame Hashira refused to perish on a deathbed in front of his family and friends.
He wanted to die as a swordsman.
A wish granted by his father, after a discussion with Kokushibo in the Infinity Castle.
Thus, the swordsman descended from Muzan fought Kokushibo.
The battle was the hardest Mori had faced since his fight against Doma.
Unfortunately, there wasn't the slightest glimmer of hope for victory on that dark night.
Only the despair of swordsmanship honed over centuries, displayed by his opponent, remained.
Mori lost.
Yet he earned the recognition of Upper Moon 1, after awakening the demon slayer mark during the night of their battle.
Kokushibo was merely intrigued by Doma's request, but he was pleasantly surprised to see such frightening talent.
He even considered clashing with Doma and offered immortality to his comrade's son.
Something Mori had once desired in his youth, but which he refused with a happy smile.
The sect leader said: "The Death ? …haha. Isn't it just the start of another adventure?"
This act surprised Upper Moon 1.
The phrase Mori uttered was well-known and taught in The Eternal Paradise Faith, and the atheist learned to embrace it at the dawn of his death.
Thus died the only son Doma ever recognized, until the arrival of the Taisho
era… killed by Kokushibo's hand.
…
Author's Note: Damn, I love killing OCs. I can't wait to kill the canon Hashira.