Walking Into Darkness

The First Step
Seireitei, the home of the Shinigami. Millions of souls dream of being counted among their number, if only to have the post, opulent living that the famous warriors took advantage of in between doing their duties to the balance of souls. Surrounded by the nigh-unbreakable Sekiseki stone, the bastion of the Death Gods remains unassailable by a vast majority of the spiritual worlds.

Sneaking in, however, was a valid idea. In a flash of fire, a young man appeared, wearing a black floor-length robe, it was hard to make out his appearance, but his mere presence set alarms off all around the Seireitei. Captains, lieutenants and low-ranking soldiers alike felt the disturbing, evil spiritual pressure that rippled in the air as the stranger walked. The young man knew he had short time before soldiers descended upon him. Another flash of roaring flame, and he was gone, reappearing at the base of the Senzaikyū, death row of the Shinigami. Inside the tower, the man knew he would find a clue to what he desired to find. Muttering under his breath, the shadow intoned a spell, sending a shockwave into the massive wooden door, rending it into tiny fragments. A bang echoed about as the handle of the door smacked into the far wall, carried by the wave of energy. Small cracks formed around the impact site.

By now, the man estimated that Captains were issuing orders to find him, kill him, and bring proof of victory back to the Division barracks. He guessed that promotions were promised to rally the troops into a desire to fight. He scoffed at the notion of combat, at least against the small fry. Had he not been withholding his full power, it'd be obvious nothing short of a Third-Seat would even be able to stand before him and even have a chance at victory. It was almost comical, the sorting algorithm that the Shinigami used to determine who fought who and in what order. Having studied every campaign his parents took part in during their tenures as Gotei soldiers. Captains had always been the last to enter conflict, even against a near Demi-God level opponent. That information alone was his ace in the hole. Centuries of theory behind it, the man laughed silently as he ran up a stairwell in search of a certain room.

Two Steps Back
In another timeline, the Seireitei's construction would have been more fortified, as well as procedural improvements in their combat order. A blonde haired man, garbed in little more that jeans and a robe tied around his waist, had almost single handedly destroyed the entirety of the area in the span of five years, even overcoming the Sekiseki through sheer will and power. He had become god, or as close to it as possible. With near-infinite power at his disposal, the world quaked in fear. Death had become but a dream, long gone. Under his rule, none were dying, none were born. Life was eternal.

Former friends stood in the way of this god, brave and foolish few they were. He respected them for their tenacity, even to the final battle's closing, he respected them. Few others had the bravery to face him down, even when it was a misguided idea. None among them could rival his might, even as a group. Only one person had a chance at landing a fatal blow, and if his divine intuition was correct, the person would have no desire to do so. His plan was nearly flawless.