In the dimly lit chambers of his laboratory, Aizen moved with precision. He reviewed a series of complex Kido formulas, necessary for maintaining the balance of Reishi in the realm of the living. Scrolls filled with intricate symbols lay before him, and with gloved hands, he sealed each one carefully. 

In the corner of the laboratory, specimens from the Menos Forest were held within stasis chambers. Their spiritual energy, harnessed for Aizen's enigmatic research, pulsed gently. 

As he focused on his daily tasks, Aizen's thoughts remained on the intricate experiments he had been conducting. His laboratory held secrets that extended far beyond the comprehension of most of the Gotei 13 captains.

Aizen was a man divided between his official responsibilities to the Soul Society and his insatiable thirst for knowledge and power. Both roles were executed with unwavering precision. His reputation as a highly accomplished Shinigami concealed the true depth of his ambitions.

With a calm expression, Aizen looked through the data of his experiments once more before he left the lab with a nonchalant pace. The man had no need to hurry, everything was as he planned it. Nothing could possibly surprise him at this point. 

Or so he thought. 

The meeting with Aisuri had come unannounced, and not without suspicion, but what truly caught him off guard was what came after. 

Aisuri had wandered into Aizen's office, lead there by his second. The rather dirty looks the woman. Kane knew that Momo Hinamori had an obsession with Aizen, perhaps stemming from some personality defect, and was surely glaring Aisuri down just for the fact that she was a female outsider surprising her and her captain, the object of her obsession, with a visit. How could she not be upset?

Kane had directed his wielder to ignore her, she was merely small dog, barking impotently at any passersby. 

Aisuri had to stifle her giggle. 

When they had gotten to the Fifth Squad Captain's office, Aisuri was pleased to see the genial and warm inflection of Captain Sōsuke Aizen staring at them. 

Kane, however, knew that he was staring at the devil. 

This was the man who killed Tier Harribel for being two weak, who attacked his lieutenant simply because he manipulated her obsession with him to the point where she 'could not live without him' and that killing her was a kindness. Aizen's crimes are more abhorrent than even Ywach. 

Kane was under no illusions of who he was dealing with, oh, no. But if he wanted to gain power, and so it fast, this was the man to talk to. 

"So," the captain began, leaning in and steepling his fingers together.  ",what do I owe the pleasure of this visit?" Aizen said with a smile. 

Kane had to hide his revulsion and hurriedly used his new power to take control over Aisuri's body before she could answer the captain. 

The voice that left the woman's lips was of a deep, somewhat Slavic accent, a manifold voice that pricked at one's hackles. 

"I am the Zanpakuto spirit, Kaatei. I come seeking an accord."

"How interesting. What sort of accord could you have with me?" He said, dismissing Momo after hearing the words from the Zanpakuto Spirit. 

Momo seemed loathe to leave, but did so rather than risk her captains ire. 

"I know everything about what has happened and what will happen." The spirit intoned, grimly, a wicked grin spreading across its wielders face. "I know that your sword is Kyoka Suigetsu, that it casts illusions. I know what you did and to whom you did it too. I also know that you fail." 

Aizens face shifts between bemusement, to shock, then to neutral passivity. 

"I fail, do I? How so?" 

"If I told you that, what use would you have for me?" 

"Haaa, you are a cunning one. But you have no proof what you say is true-"

"One hundred years ago, you used your Zanpakuto's command to fool your predecessor and former captain Shinji Hirak-"

"Enough." 

The expression on the man's face was serious, almost angry. 

"What do you want?" Aizen said, voice dripping with scorn. 

"Why, I want what all weapons want; to kill. The proposition is simple. You give me a way to get to Hueco Mundo, and once a week, I'll answer any once question about anything you may have." 

Aizen leaned back in his chair and took a deep breath, his thoughts racing. Finally, he sighed and wrote something down on a paper. "This is a custom Kido spell that opens a Garganta. This should allow you to go to Hueco Mundo as you please. Now. My first question." 

"Speak."

"How do I fail?" 

"...Ichigo Kurosaki."