Bear with me here. Read the whole chapter. It shows the subtle changes, even if they aren't big.
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For a while, no one said anything. The Great Toad Sage remained silent and allowed Tenji a moment to himself.
Tears ran down Tenji's cheeks as he observed his love fighting their sons. It tore his heart apart and shattered the will he had built up to find all of them. His face was filled with immeasurable pain, but he forced himself to watch the entire battle. After a while, Gamamaru continued.
"Finally, after a very long time, Hagoromo and Hamura succeeded. Unable to kill their mother and also unsure what might happen to the people captured by the Divine Tree, the brothers sealed her instead. The people who had been bound by the Divine Tree were freed. Hagoromo split the Ten-Tails into nine tailed beasts, whom he raised and taught personally. Having been closer and more sensitive to Kaguya and her feelings, Hamura understood her fears and decided to depart for the Moon to watch over her.
After Kaguya was sealed, Hagoromo began wandering the world to restore the lands ravaged by the fight against the Ten-Tails and to find homes for the tailed beasts. I gave Hagoromo another prophecy, about the tailed beasts and a "blue-eyed youth", and bid him farewell. The details aren't important right now.
Hagoromo came across a broken bridge and decided to repair it, despite Futami's protests, a thief who used it to scam and steal from people. Hagoromo warns a would-be victim about him, enraging him. After days of watching Hagoromo restore the bridge, Futami himself began helping, so Hagoromo could leave sooner, intending to destroy the bridge again after he left. Seeing the two rebuilding the bridge, others began to help.
After the bridge was built, Futami left with Hagoromo, having changed his path and come to understand Hagoromo's new path and goals. After getting to know each other more, Hagoromo even shared his chakra with Futami, who asked to become his apprentice. Hagoromo had then discovered another purpose for his journey. He came to see Chakra as the means of bonding with people. The two came across another broken bridge, and another thief, and the situation repeated itself.
Hagoromo began amassing more followers, found places where he could release the tailed beasts, and started raising them. Hagoromo's followers scattered, spreading the way of Ninshū across the world. After his journey was done, Hagoromo returned to the Land of Ancestors, where he married and had two children, though his wife passed away after giving birth to Asura. Those are your two grandsons."
Tenji continued to watch the Memory Stone. The tears had stopped flowing somewhat, but hadn't dried. The pain was still very much present and not processed in the slightest. He didn't say a word; instead, he chose to observe.
"It quickly became clear that Indra had inherited more talent compared to Asura. Indra effortlessly covered volumes of Hagoromo's writings in the span of a few sittings, while Asura struggled more. But Indra had a vast, gentle heart, always looking after his younger brother, whom he loved above all else.
Indra showcased his immense talent at manipulating chakra to his father, brother, and other ninshū followers. He had created ways to shape Chakra. He started calling the hand formations "seals" and the effects "jutsu". Indra's innovations changed ninshū, giving it practical and everyday uses. But Indra was an immense talent, capable of understanding the effects of his innovation.
During an incident, Asura and his friends were attacked by a wild boar, which killed their dog, Shiro. Asura, who preferred to spend his time with his friends and play around, struggled to perform ninshū in time to defeat the boar. Thankfully, Indra arrived to save him, awakening the Sharingan's power, similar to Hagoromo's eyes in the past.
The incident made Indra grow harsher, more isolated, and more focused on performing jutsu. His fear of losing the brother he loved so much made him chase perfection and strength above all else. Indra grew adamant that crimes should be punished to deter future crimes, much like his grandmother, Kaguya, did during her time.
The day came when Hagoromo was to decide his successor as the leader of Ninshū. However, instead of choosing Indra as the obvious successor, Hagoromo handed them scrolls, each one with a location that was damaged by the fight against the Ten-Tails. Hagoromo wanted each to go to the area and solve whatever problem remained. He told them that he would pick his successor based on the results.
Asura was baffled by Hagoromo's decision, having neither the drive nor the desire to take over Ninshū, and was willing to simply aid Indra.
Asura was followed by his friend, Taizō, who explained that after Asura told his mother what Asura had done for him, she told him to aid him on his journey. The two journeyed to where the Divine Tree used to be, finding a village there. After a slight misunderstanding and a show of kindness on Asura's part, they were welcomed into the village. He wasn't in a hurry to complete his quest and was more concerned with connecting with the people first. Asura decided to go to the Divine Tree and was aided by Taizō and Kanna after realising it was most likely the cause of the people's poor health. The three ventured down a cave among the Divine Tree's roots and found the cause of the village's disease and other problems.
Asura understood that the sap of the Divine Tree was what was making people sick. It acted as a fertiliser to the land, and when people ate food grown in that land, the sap built up in their bodies. After reaching this conclusion, Asura, Taizō, and Kanna spoke with the village elder about the Divine Tree's effects, with Asura explaining that he had been sent to address it.
But the elder explained how dire their situation was before the Divine Tree began nourishing the land, with yearly droughts and countless deaths from starvation. They accepted the harmful effects of the Divine Tree's sap because the alternative was starvation. Asura was faced with a choice. Either he could use ninshū to destroy the sap, or he could respect the people's wishes. Neither option was good in his eyes, as he hated forcing his will on others and despised violence."
Tenji watched his grandson come up with a clever solution, one he would have taken as well. Although Tenji wouldn't have had trouble convincing others about what had to be done, he was still rather proud at seeing his grandson and his friend Taizō start digging a well. The ground was very hard and full of stones, promising a long time of hard work. But Asura was convinced it had to be done that way, happily accepting his friend's help. Asura was talented in using ninshū; he wasn't close to his brother's. But his approach was exactly the same as Hagoromo's had been when he went on his journey.
"Seeing Asura's hard work and sincerity, the villagers started helping him, sharing the burden but also the excitement, when they succeeded two months later. Instead of leaving right away, though, Asura completed his objective and destroyed the Divine Tree sap and healed all those who were sick. Asura went above his work, though, and even taught the village Ninshū. 6 months after he had set out, Asura returned with a group of friends who wished to join him.
Indra, on the other hand, did things differently. Instead of respecting the villager's wishes, he took charge forcefully and destroyed the Divine Tree, making the water pure again. He did this in a matter of one day and then returned. But what he didn't see was that after he had gone, the villagers began fighting over the water rights and almost destroyed the village. When Asura returned, Hagoromo revealed who he chose as his successor.
To everyone's surprise, it was Asura."
Tenji continued to watch as things spiralled out of control. He saw the hurt in Indra's eyes and the confusion in Asura's. Neither of them acted as they should have. Indra stormed out. Tenji saw everything play out. The celebrations were held for Asura's appointment and then the moment Indra returned. He attacked the celebrations and revealed that he had, as Hagoromo had before, evolved his eyes into the Mangekyo Sharingan.
"Indra used the Susanoo, which he had gained access to and fought against Asura, who had inherited Hagoromo's powers. And still, unwilling to harm his elder brother, whom he still loved, Asura finally acted when Indra attacked the settlement and his friends. Those who saw the fight supported Asura, making it a very easy victory for Asura. Indra vowed never to acknowledge Asura and to fight him forever."
Finally, Gamamaru stopped talking and only let the many deaths and fights speak for themselves. He showed Tenji the final moments of his son, Hagoromo, until the Memory Ball turned white again.
"Despite not needing it, Asura refused to fight his brother until he attacked his friends actively. It was his friends who actively supported him, which made him into the man he later became. One brother is so much like his father, Hagoromo, and the other is so much like his grandmother, Kaguya. Their battles went on for a thousand years and only stopped a few years ago, when Hashirama Senju and Madara Uchiha set their clan's hatred aside and created the Hidden Villages."
Tenji's face had darkened. He was grieving the fate of his family. It seemed that his sacrifice had yielded nothing. His absence left a wound which couldn't be healed. His sons weren't brought up as he'd hoped they would be, leaving his wife with all that weight to bear. All the additional talent had only increased the damage and the speed of the battles. Hagoromo and Hamura defeated their mother far quicker than they would have otherwise. And both Indra and Ashura were more powerful as well. This led to greater destruction and deaths.
"Why have you told me all of this?" Tenji asked.
"You needed to know the past, to be ready for the future. The times will change greatly, and I foresee even more wars and greater danger. A boy with blue eyes and a bright smile will bring great change to this world, and you will play a significant role as well. You are capable of tilting the balance in favour of peace, like you wanted," Gamamaru said.
"So you don't know what will happen. You haven't seen that far; otherwise, you wouldn't be talking to me and trying to influence me. I guess that you fear what I will do now and hope that I will do as you want... Just like my son did."
"Huh?!!"
"Did you think I wouldn't notice? The images you showed weren't complete. I am certain that it was you who brought the Divine Tree to Hagoromo and Hamura's attention. You taught him Sage Power and basically pitted my sons against my wife. The answer was easy for you because you didn't know any better. You think you understood Kaguya, but you didn't."
...
"What do you mean?" Gamamaru asked.
"My Kaguya loved this planet, and she loved humans. She loved them enough to go against those who would kill her for 'feeling' the way she did. She was carrying all that weight on her shoulders, and then the two closest to her heart, those she thought were on her side, unconditionally, went against her and sealed her."
"..."
"All this time, you were alive, you had the chance to change things, but didn't do it. You hide here in this land, while you could have taken an active role. I am disappointed in my sons' choices, but no amount of talent can grant someone maturity and life experience. I promised to kill the one responsible for what happened. And should we meet again, that will happen. Sadly, it seems that I am as much to blame for this. I shall learn from my mistakes."
Tenji kept his thoughts and feelings to himself. He turned around and started leaving.
"What will you do now?" Gamamaru asked.
The Great Toad Sage was worried. Not only because his plan had failed, but also because the possibility that Tenji would affect things was severe. But he was also concerned about Tenji's words and their implication. He had never bothered to really find out 'where' Kaguya came from.
"Leave," Tenji said.
"Leave where?"
"To acquire a sword. And then... I'll get my wife back."
The toads watched Tenji walk out and felt him leave Mount Myoboku. No one dared to say anything until Gamamaru's laughter pierced the silence.
"Hehehehehe..."
"What are you laughing about?" Fukasaku asked.
"That Tenji... in the short time he was here... he grasped Sage Power..."
"WHAT?!" "HUUUH?!!"
"Truly unfair talent. To think that Hagoromo and Hamura were so ordinary compared to their father... I wonder..."