Notes: written pretty much as soon as Kaguya was first introduced! this is still my headcanon but it's fairly AU now.
The first step Kaguya took upon the shore of this new land was marked with blood.
Not hers, of course, but blood nonetheless, darkening the sand. Soon, she discovered it was everywhere, no matter where she went. Blood, and corpses, and the struggle over land or wealth or power. Human against human, with only the law of the strong prevailing. It was disgusting. She pitied them, but there were too many dead to bury or burn, too many wounded to heal.
Her appearance and knowledge led some people to her, and they called her Princess. If she had wanted, she could have formed an army, taken lands for herself and lived. Perhaps her strength alone would have been enough to carve out borders, enforce peace and protect at least some people from the wars that raged on and on and on. But that wasn't enough, not when the world outside would tear itself apart.
No matter what she did, people would grieve, and give into hatred and vengeance. The only place where peace held was at the base of the Shinju. No matter how desperate the people, how hateful and bitter the anger that drove armies against each other, no one dared disturb a god.
Perhaps it was because she was not of this land, and not born with respect for a deity that did little but grow and bear fruit. Perhaps it was because she was weary of blood and death already, and longed for something new and clean and peaceful. Perhaps it was just selfishness, that her pride alone could not bear watching so much waste.
She climbed the Shinju, though its divine power burned her hands. She ate its fruit, and felt its power sing in her veins, and when she set foot upon the ground, it trembled. So what if this was forbidden, heresy, stealing from the rightful god of the world? What use was a god that did little more than grow, that was so aloof from the world that it couldn't begin to comprehend the struggles of the people who worshipped it?
Better a demon and a thief than that, surely.
So she walked across the land and brought it to peace, for no army could possibly stand against her. In her wake there was silence, but the land was renewed, grass growing where bodies had lain, and she healed the wounded and struck down the defiant.
In the end, Kaguya ruled, because who else? The Shinju's power was hers, and no one could contest that. That she was alone and distant was an acceptable burden. And when she had given birth to two sons – both of them with the same power as hers, she couldn't bring herself to feel anything but triumph. Through her, this world would have hope for something better than endless strife.
And even the roar of the Ten Tails as it cursed her could do little to change that.