Just because Hades was gone didn't mean there weren't things to fight.
The Underworld naturally spawned monsters. They were born out of resentful souls who would not be reborn.
Monsters meant fights and experience.
He was doing them a service, really.
Defeating these fiends released the souls. Off they went to be reborn. Hundreds would replace them, sometimes the same ones who hadn't gotten rid of all their resentment.
Nobody was monitoring the Underworld, really. He was the only one down here, exploring, fighting. If it weren't for him, the flow of life might actually stop. And nobody would know why. Until the gods finally noticed. Until the gods finally squabbled over the Underworld, and fixed it.
Yes. He was doing them a service.
Without Hades' influence, the Underworld was actually a pleasant place, if you didn't count the fiends and occasional leftover Underworld troop. All darkness and cool lighting and unusual places. Medusa's favorite fiery inferno was far to the west, and no souls went there anyways. It wasn't natural, actually- she'd made it herself. And Hades' twisted influence was gone, making the Underworld a spacious, infinite cavern.
And all his. For now. He liked it here. He liked the cool, damp places and the lack of harsh lighting. Kuro supposed there was a reason he liked darkness so much, but he ignored it.
There was also a steady stream of payment to be had.
Here he could be himself. There was nobody down here to possibly find him, unless some god's champion wandered in. He gleaned trophies in the form of weapons and hearts. The hearts he scattered amongst the weakened souls that littered the darkest corners, waiting to regain strength. He had no need of them. He had no god to give them to.
His claws tore into the ichor of another fiend, and he grinned fiercely. Of course, these creatures were more satisfying kills. Born of resentment and the darkness of souls rather than the will of any god, they were stronger, fiercer. The energy of the strongest coalesced to make godly weapons.
The lupine creature howled and broke apart into pale wisps. Kuro collected the hearts and moved on.
He was approaching the city of souls. He could see the city's tall crystal spires in the distance, and the souls seething and passing about the base. He turned aside. The Rewind Spring was there, and he might accidentally revive the Cloud Dragon. Further on he could see the torrent of souls, starting to ebb into a less furious flow.
To his left was a hill. It was... green?
Green, with growing things.
He hadn't been here before. Kuro landed, the power of the winds dissipating from his wings. There was a forest here. How, where there was no sun? But no- there it was, high above, imprinted on the dark, distant sky-cieling of the Underworld like a-
Memory.
There were soft giggles. Small, pale forms danced amongst the trees. Two soul-made, small girls came out from the undergrowth. Their eyes were blank sockets. He stiffened as they approached, mouths open in smiles that were no doubt charming in life. One tugged on his tunic to offer up ghostly flowers. Automatically, he took them.
And the scene changed.
The girls vanished, replaced by a blank darkness over the barren soil that was the Hill of Memories. Even the ground was blackened. Kuro walked, confused. What was this supposed to-
There was a ring on the ground, a ring so small and insignificant he almost missed it. Kuro picked it up. Silvery as it was with soul-stuff, he had little idea of its original coloration. He turned around and came face to face with-
Himself.
It WAS him, not Pit, because the clothing was dark. His eyes were blank, his mouth gaping in fear, and he realized what he was holding. The Ring of Chaos. When he- had been less than nothing. All because of Pit. Because he was connected to Pit. Because- he was his copy.
"NO!" he roared, turning and taking off, the silvery ring slipping from his fingers. No. No! He wasn't Pit's copy. He didn't rely on him. He was himself!
There was a dark orchard. His wild flight pattern crashed him in it. Kuro felt pain flare through his wing, and blacked out.