A Chilling Alliance

For the first time in several decades, Sōsuke Aizen set foot in the Reikaitei world of Aether. "What a sight." he commented as he began to walk through a dense forest towards a large fortress. "It seems that this is where all that reiatsu is coming from." He walked into the building without any hindrance and found his way to a room that had no ceiling to it, but was instead open to the sky. A rock formation was erected in the center of the room and its peak stuck out beyond the roof. Halfway down on a ledge sat a shady figure. "Aizen Sōsuke..." came a chilling, serpent-like voice. "I was wondering when you might appear."

Aizen flashed his signature arrogant smile, "So, one such as yourself believes that you have anticipated my actions? How arrogant." Aizen retorted. "Now, now, Sōsuke. No need for that kind of talk here." said the snake-like voice. "Why have you come here?" Aizen narrowed his eyes, "Do you think that I would allow you to continue your operations here without coming to destroy you, Muramasa Neikan?" Aizen asked. The snake-like Muramasa chuckled where he sat, "I was under the impression that you didn't have a choice." he amusingly stated. Aizen drew his sword and held it up to the moonlight, "Perhaps, then, its time to show you how fearsome I really am." he declared. The release of the sword never came. The robed Muramasa had amazingly appeared before Aizen with his hand on the blunt end of Kyōka Suigetsu. "It won't work, Sōsuke. You forget, I have crossed blades with Lucius Ichimaru who knows the weakness of your Kyōka Suigetsu. You're no match for me if all you are going to do is use that parlor trick." Muramasa threatened.

Aizen grinned again, "How crafty. Perhaps then, the will of the Hōgyoku will grant me victory." he retorted. Muramasa was quick in summoning a Kidō barrier around Aizen. Suddenly, the black orb in Aizen's chest floated out and was locked up in an adjacent barrier. This visibly angered Aizen, though his voice did not hint it, "I applaud you for being able to use Shinigami Kidō." he said. Muramasa smiled his own deceptive grin, "Is it so surprising that a Bount can use Kidō, Sōsuke?" he asked. "The Hōgyoku rejected you as its master decades ago, but it will still serve me some." At this, he took the orb out of the barrier and slid it into his robe pocket. "Since I now have your attention, I'll make you a little proposal. You will supply me with all of your research pertaining to Arrancar and the Hōgyoku and I'll give you a chance at revenge." he offered. Aizen narrowed his eyes, "What makes you think that you can propose me something?" he asked arrogantly. Muramasa only smiled and teleported the two into the lower catacombs of the fortress.

The Army Lies in Wait
They were now in a massive underground chamber that had at its center, what appeared to be a tree of bone. Aizen's eyes widened, "Is that...?" he stuttered. Muramasa nodded, "Its in his released state; Arbol." he stated. "How did you get him? How did he get so big...?" Aizen asked. "So many questions today Sōsuke." Muramasa commented, amused. "You did a bad job of cleaning up your mess in Hueco Mundo, so I collected the corpse and transported it here. I then modified him in order to allow him to produce his calaveras even though he was dead. I also expanded the size of his released state in order to allow him to grow more at one time." he explained. Aizen was clearly shocked, an emotion he rarely felt. Just below Rudobōn's tree-like form, the floor of the immense room was covered with dormant calaveras. "How many are there?" Aizen asked. Muramasa grinned, "Well over a million. I need soldiers to complete my plan after all." he replied.

"Why are you showing me this?" Aizen grunted. "To show you that you are helpless and that you must accept my proposal, or become subject to my experiments." Muramasa retorted. Aizen sighed in defeat, "Very well." he replied. "Excellent." Muramasa said, releasing Aizen from his barrier. "Now then, I must show you something else." Muramasa took Aizen further into the catacombs of his fortress until they came to another large room which was mostly engulfed in a large Kidō barrier. The barrier was filled with millions upon millions of small mosquito-like creatures. Aizen was again visibly disturbed, "W-what are those?!" he asked. "They're called bitto. They're a creation of the Bount; a variation of our Dolls that suck out the souls of Humans, Shinigami, and Hollows and turn them into an elixir that increases our strength. This army of bitto will make it's debut very soon..." Muramasa explained.

Aizen nodded, "Where do I come in?" he asked. "You'll do what I told you to do earlier. You'll get your revenge. Doing that will distract the Shinigami until my preparations are complete. Then we'll begin the war to end all wars." Muramasa replied. With that, he teleported to make other preparations, leaving Aizen to his thoughts...