The "realistic" isekai protagonist is basically where the protagonist has to suffer on their journey. Leaving aside the one who suffers because they don't get a good ability. He thought more about the one who is strong but couldn't protect the people he loves.
Now, as a librarian, he understands that there are infinite timelines in a single reality, and the version that most people know is the one where everything goes well, why? Because it generates the most energy of destiny.
There are too many versions of a "protagonist" who lost everything.
In "realistic" isekai, before the real protagonist messes it up, the previous version of the protagonist expends all of his power to send a message to the past and prevent the other version of him from making the same mistakes.
This fear rekindled his determination.
The possibility that he himself would become the version full of sorrow and loss propelled him. Being used solely for another version of himself to have a happy ending is something he would not accept.
The doubt of changing to obtain power was lost.
Now, he would focus solely on strengthening himself and wouldn't allow remorse to dominate him. It would not focus solely on the power of destruction.
He set out to achieve perfection in all aspects and wouldn't rest until he accomplished it.
This change in his mentality marked a turning point: he took the simulations as they were, avoiding any emotional ties and refraining from forming alliances.
Daniel immersed himself in direct battles with gods, unwavering in his goal to wrest their power from them.
After vanquishing the gods, humans glimpsed a ray of hope that quickly dissipated when Daniel turned against them. Among the humans there were people who could defeat the gods, they also needed to take everything from them.
The massacre extended to the titans. When the valkyrie thought her plan of being a lovesick bitch worked, he killed her lover, killed, and absorbed any being powerful enough.
In the end, simulation was left in ruins. The weaker ones fed his World Tree, which in turn nourished his soul. This marked the beginning of Daniel and his journey amidst the devastating simulations.
Anticipating his future change, Daniel ordered,
"Clarion, create a backup of my self before obtaining power. Hide it deep within my soul and make it impossible to erase. Place a heavenly restrainton my soul so that it doesn't harm my loved ones (his mother, Ako, and his grandmother), nor involve them in my future plans. Duplicate this restriction for their use as mere pleasure tools.
Also, impose a minor restriction to prevent harming small children and those of pure and innocent hearts, with an exception if they are naive idealists."
"I will do as you've instructed, master."
"Also, don't allow me to forget the distinction between reality and simulations when the time comes, Clarion."
"I began reading psychology books a while ago, master."
"You're the best, Clarion."
------------------------------
"Clarion, how much time have we been here?"
"6 years, Master."
...
"Clarion. Time."
"10 years, Master."
...
"Clarion, time."
"34 years, Master."
...
"Clarion," Daniel whispered.
"124 years, Master."
"... I'm so tired," confessed Daniel.
"Master, why not rest and go see your family? You're strong enough now, we can handle the final part of the plan later," Clarion suggested with understanding.
"I don't know, Clarion. Before, I was afraid of encountering the conceptual beings that control everything from the shadows. I wanted to control my life without fear.
Now, I just want to do what I want, challenge those who oppose me, and protect my family. We're close to finishing, only the hardest part remains,"
Daniel said with slightly dark eyes, but with an unwavering determination.
"Master..."
"Also, because I know myself, I'm a person who likes to work excessively for a season to rest for a lifetime."
"..."
--------
"... Clarion, I'm ready. Sacrifice the lesser concepts and souls for the development of the "Reality" concept, and give me the estimated time for the incorporation of concepts."
"Approximately 1 year per concept, the concept of reality will take 1,345 years," Clarion informed.
"Clarion, create a new backup of my life."
"Yes, Master. Good luck."
------------------------------------
In a meadow with giant shelves scattered around the place, a woman with hair as golden as gold patiently awaited her master as she read.
"I'm tired of reading books. Being surrounded by books becomes annoying. Now I understand why humans refer to feeling claustrophobic," murmured Clarion, who had accompanied her master all that time.
While Daniel was in a state of absolute concentration, merging with the concepts, Clarion waited for him like a wife waiting for her husband to return from work.
She created a physical body to be closer to her master. Now she was a little shorter than Daniel, but still as beautiful as a fairy from fantasy tales.
Suddenly, the library lit up, and the entire landscape changed to a field full of flowers.
"Ah, he's awakened," said Clarion when Daniel finally managed to complete his last concept.
Upon awakening, the first thing he did was completely change the scenery, as he, like Clarion, had come to despise books after so much time.
"Clarion," Daniel called.
"Here I am, Master. Congratulations on completing your concepts," Clarion replied.
"Show me the system."
[Omniversal System]
User: Daniel Ashikaga
Race: Primordial God
Level: ---
Title:
Assets: The Beginning of All, The End of Nothing, Omniversal Librarian, Trojan, Son of Luck, Miracle.
Deactivated: Protagonist, Antagonist, Hero, Demon King, The Savior, The Chosen One, Massacre, Evil God, Thief…
Concepts:
Primary: Reality
Secondary: Time, Space, Matter, Existence, Mind, Soul, Energy, Power, Destiny, Luck, Laws, Life, Death, Creation, Destruction, Beauty, Realism, Subjectivity, TooN, Evolution, Absorption, Theft, System, Magic, Sword, Combat, War, Martial Arts, Healing, Restoration, Virus…
Inventory: Multiversal Tree, World Tree x7, Universal Panacea x1259, Protective Gems x875 (self-made), Armors x34, Fountain of Youth x345, Weapons x356, Pills x1643, Food x6543…
"It seems it has compacted a bit, I don't even have my abilities anymore."
"I considered it unnecessary, everything generates from a concept, Master."
"Not a complaint, Clarion, just an observation."
"I hope so, it took a lot to arrange and classify all your things."
"I know, I know, come here, give me a kiss." Daniel opened his arms ready to embrace Clarion; all this time, Clarion had been the only real person with him, at least in his eyes.
"Just this once."
…
"It's time to go back, Clarion. I miss my family."
"You say that, but you've forged so many gems for women."
----------
Note:
With this his creation of powers and world ends, his journey begins.
Have a good day, eat well and be happy.