Sōsuke Aizen

"No one stands on the top of the world. Not you, not me, not even gods. But the unbearable vacancy of the throne in the sky is over. From now on... I will be sitting on it."

- Aizen to Ukitake "I suppose it is only to be expected. You have my pity. There is no such thing as 'truth' or 'lies' in this world; there never has been. There is only plain, hard facts. And yet, all beings who exist in this world take only those 'facts' that are convenient to them, and take them to be the 'truth'. They do so because they know no other way to live. However, for those powerless beings that make up the majority of this world it is those 'facts' that are inconvenient for their own self-affirmation that make up the real 'truth'."

- Aizen to Ichigo Kurosaki.

Sōsuke Aizen is the former captain of the 5th Division in the Gotei 13, before he leaves Soul Society and the original main antagonist of the anime/manga series Bleach.

He is voiced by Shō Hayami in the Japanese version of the anime and Kyle Hebert in the English version, the former of whom also voices Enrico Maxwell.

Personality
Aizen is completely calm and cold, having a very polite and knowledgeable manner about him and rarely showing an signs of alarm. He often tries to make small talk with his enemies so as to anger them. Aizen has an extremely cruel and dangerously manipulative nature, caring nothing for any of his subordinates and to him, they are all just pawns for him to use. He states that he doesn't have any morals, saying they just restrict his capabilities.

Aizen will stop at nothing to complete his plans and thinks of long and complex (as well as somewhat convoluted) plans. He often toys with his subordinates and controls his forces through respect, intimidation, fear, and mind games with only Gin being able to figure out Aizen's emotions. Aizen’s objective is to overthrow the Spirit King and states that he seeks to “stand in the heavens and end the unbearable vacancy on the world’s throne”. After mastering the Hogyoku, Aizen seems to have become less cautious in battle and has more of a severe superiority complex. He does not think through his moves as much and believes that he is above Shinigami and Hollows. His intelligence and attitude make Aizen easily angered when heis fighting something he does not understand.

Powers and Abilities
Genius Intellect: Arguably, the most fearsome trait of Aizen is his tremendous intellect. He is well-versed in the history, strategy, and tactics of Soul Society, and is privy to knowledge unknown to many, such as the existence of the Ōken and its method of creation. He has created several Hollows and Arrancar while avoiding any suspicion from the majority of Soul Society. For over 110 years, he had been engaging in experiments involving unique and highly dangerous manipulations of Reiryoku and Reishi, including experiments involving the Hollowfication of Shinigami, something which had never been done before. He has an innate knowledge of the Hōgyoku, rivaling that of its creator, Kisuke Urahara, even knowing how to destroy it. He figured out the true nature of Shinji Hirako's Shikai, allowing him to counter its effect. He effectively deduces the true nature of the Hōgyoku via trial and error of the situations which revolve around it.
 * Master Manipulator: Aizen has proven himself very crafty and a cunning man since his public betrayal of Soul Society. He can deceive and manipulate others around him in different ways for a variety of purposes. For years, he convinced everyone around him he was a kind-hearted man with the best intentions for Soul Society while performing horrific actions. He has a great talent for analyzing and observing everything in his presence, allowing him to understand a person's pattern of thinking and better manipulate them. He can formulate well thought out plans several steps ahead of others, some of which have a long term in mind. His most well-known plan spans over 110 years, a great accomplishment which involved moving people around like pieces on a chessboard and making sure they played the role he had planned out for them. He is masterful at plans within plans, such as kidnapping Orihime, allowing him to use her abilities to extend the shelf life of the Hōgyoku and lure many of his enemies into Hueco Mundo to trap them, making it easier for him to accomplish the goal invading the Royal Palace. He can shatter the will of others. He has unnaturally high charisma, enabling him to gain the trust and loyalty of others and gaining significant influence over others.
 * Master Strategist & Tactician: Aizen has proven himself to be a flawless and flexible tactician, adjusting seamlessly to any given situation, if not planning out events well in advance. He understands the strengths, weaknesses and mannerisms of his enemies, and creates strategies to achieve victory; this includes modifying an Arrancar for the sole purpose of defeating Captain-Commander Genryūsai Shigekuni Yamamoto, a Shinigami whose abilities surpass his own.  Aizen is highly cautious, and leaves no blind spots. He is capable of consciously focusing, and being fully aware of multiple people, dangers, locations, tasks, etc., and processing all of it at once without any trouble or confusion.  He can notice, process and understand any/all details of any situation or environment no matter how small, allowing him to intuitively understand and solve any problem or situation no matter how difficult or impossible it may be.
 * Shunpo Master: Aizen is so fast, opponents commonly cannot discern even being attacked by him until after it has taken place. Aizen can dodge simultaneous attacks at close-range and even when being attacked from behind.
 * Immense Strength: Aizen is strong enough to stop the blade of Ichigo's Bankai with just one index finger and almost cut him in half with a single sword strike. He stopped Renji Abarai's Shikai with his bare hand and broke it with one swing, injuring Renji in the process. He stopped Komamura's Shikai with his bare hand, proving his strength is more than enough to combat someone of the same level.
 * Immortality: Aizen attained immortality and nigh-indestructibility, he kept regenerating himself no matter the damage, resulting in the necessity to seal him away deep in the underground prison. After being hit by Ichigo's Mugetsu, Aizen restores from the damage. He is later confirmed by Central 46 to having been left immortal by his interaction with the Hōgyoku.

Aizen possesses immense spiritual power, even for a captain-level Soul Reapers. He possesses incredible intellect, having knowledge on many things and high craftiness and cunning. Aizen is extremely skilled at manipulating others and always thinks a few steps ahead of his opponent and thinking out incredibly detailed plans with many steps. Aizen is able to adjust to any kind of situation in battle and has a great understanding of his foes, thus he can prepare to deal with them. Like all Soul Reapers, his primary weapon is his Zanpakutō, Kyōka Suigetsu, and he can activate and deactivate its Shikai ability with the release command, “Shatter”. Its ability is the power to completely hypnotize the opponent, controlling their senses so Aizen can create a variety of illusions to trick them.

To hypnotize the person, they have to see the release of Kyoka Suigetsu and from then on, the person will be completely under the hypnosis’ power. The influence of Kyoka Suigetsu can last for years as seen with the Visoreds, who were first hypnotized 110 years ago. The hypnosis can even affect the person if they are aware that they are being manipulated by it. However those with great power and ability can notice slight differences in the illusions, even if they can’t determine what they are. The only way to avoid being controlled by Kyoka Suigetsu is to touch the blade before its hypnosis power is activated. It is presumed that since Aizen is a captain, he can release the Bankai form of Kyoka Suigetsu, but he has never been seen using it. However, after his evolution prior to his capture, Kyoka Suigetsu corrodes away as his Zanpakuto's power has become a part of him. With the Hogyoku planted in his chest, it regenerates all of Aizen’s wounds and increases his strength and durability.

After his first transformation by the Hōgyoku, Aizen is in his “chrysalis” stage, possessing higher spiritual power, and increased strength, durability, and speed. After finishing his “chrysalis” stage, Aizen was even harder to harm, destroying the Kōtotsu by just having it collide with him, and even higher spiritual power, able to destroy souls just by being around them. In his third form, Aizen had greater strength and could teleport by breaking into shards, then reforming elsewhere. After transforming for the last time, he has a much more Hollow-like appearance and can fire powerful energy spheres from the skulls on his wings, as well as surround his opponent with an energy ring to destroy them.

Quotes
"How unfortunate! You found her? Pardon me. It wasn't my intention to traumatize you. Before you could have noticed, I should have chopped her into unrecognizable pieces."

- Aizen to Tōshirō Hitsugaya upon his discovery of an injured Momo Hinamori.

"You should learn this well, Hitsugaya-kun. Admiration is the emotion furthest from understanding."

- Aizen to Tōshirō Hitsugaya.

"The Sōsuke Aizen you knew...never existed to begin with."

- Aizen to Renji Abarai.

"You should not dwell on the betrayal that you can see. The truly terrifying betrayal is that which lies utterly hidden from your eyes, Captain Hirako."

- Aizen to Shinji Hirako.

"I never even dreamed that the power of the ten Espada I went to so much trouble to gather could possibly be inferior to that of myself alone."

- Aizen to Tier Harribel indirectly.

"To trust in another is the same as to rely upon that person. Reliance is for the weak. It is of no use to us."

- Aizen to Shinji Hirako.

"It is the nature of all living things to find some being greater than themselves and place their trust in that being, following it blindly. In order to escape from the pressure of that trust, those beings seek a still greater entity in which to believe, and those greater beings too seek still greater, still stronger beings to follow. This is how all kings come to be, and this is how all Gods are born. Do not trust in me yet, Hirako Shinji. I will take my time to teach you the nature of the God whom you face. Then, you shall believe."

- Aizen to Shinji Hirako.

"Why do you insist on keeping such distance from me? If you wish to make a decisive strike, you should do so at point-blank range. Or perhaps you are afraid of moving in too close, and letting even a part of my body out of your sight? If so, I am disappointed. Keeping one's distance is only a key factor in a battle between two combatants of equal strength. Between you and myself, distances hold no meaning whatsoever. Observe. I am perfectly capable of reaching your heart at any moment."

- Aizen to Ichigo Kurosaki.

"Did you think that a display of force would be enough to overwhelm me? How foolish. In fact, I would say that the very concept of 'power' itself is different for me than for you. Allow me to demonstrate. This is the true meaning of 'power'."

- Aizen to Sajin Komamura.

"I will not take your lives. With the measure of power that you possess, you are unlikely even to lose consciousness from those wounds. Stay there, helpless and defeated, and observe carefully as this battle reaches its conclusion."

- Aizen to Shunsui Kyōraku, Tōshirō Hitsugaya, Suì-Fēng, and Shinji Hirako.

"Your Ryūjin Jakka is indeed the most powerful Zanpakutō in existence. There is no doubt about that. Were I to fight against it directly, it would likely overpower even me. However, if one abandons all other abilities and focuses his strength entirely on a single specialized skill, then he can overcome even the greatest of powers."

- Aizen to Genryūsai Shigekuni Yamamoto.

"Cruel? Once a soul has become a Hollow, it holds no meaning. It is a being with no purpose beyond idly consuming its fellow souls. Where do you see cruelty in my giving purpose to such a being? Surely the true act of cruelty was your tearing that soul to pieces."

- Aizen to Genryūsai Shigekuni Yamamoto.

"I will not do you the injustice of refusing to take your life. You, who are the very embodiment of the history of Soul Society itself - you alone will die here by my blade."

- Aizen to Genryūsai Shigekuni Yamamoto.

"The Hōgyoku is able to manifest the desires of those around it. However, this manifestation will not be successful unless the possessors of those desires have the strength to carry it out. In a way, its ability might be better termed a 'guiding force'. However, it is a peculiar quality of living beings that when it comes to achieving those petty desires that their crude hearts enshrine, they tend to have remarkable levels of success."

- Aizen to Isshin Kurosaki.

"Why not be careless? I no longer have any need to take care. I can feel it. Now that my body has subjugated the Hōgyoku, it has begun to far surpass even the capacity that I once possessed - a capacity that already held no equal in Soul Society. There is no longer any need for me to evade even a Kidō ranking in the nineties!"

- Aizen to Kisuke Urahara.

"The laws of nature are for beings who must live their lives bound by them. Now, shall we carry on? To a place beyond all laws."

- Aizen to Gin Ichimaru.

"Fear is necessary to achieve evolution. The fear that, in one's current state, one could quite possibly be destroyed at any time. I thank you, Gin. It is thanks to your presence that I have finally succeeded in surpassing both Shinigami and Hollows."

- Aizen to Gin Ichimaru.

"Those are the words of a defeated man!! A victor must speak not of the current state of the world, but of how it should rightfully be!"

- Aizen to Kisuke Urahara.

"So if you are killed, the gate to Muken will be closed for all eternity. Did they expect I would go so far as to take your life in order to steal the key to this place? I never did like those old fools in Central 46..."

- Aizen to Shunsui Kyōraku.

"I must say... You truly are an entertaining man. Would I like to breathe fresh air, you ask? Would that be the fresh air of a Soul Society being summarily crushed by Yhwach?"

- Aizen to Shunsui Kyōraku.

"This is not about benefit. My only purpose has always been to crush all who seek to control me."

- Aizen to Yhwach regarding their battle.

"Yhwach, the world that you desired to create may indeed have been devoid of fear. However, in a world without the fear of death, men could not face that fear and seek out hope. Certainly, they could keep walking onward by merely living, but that would be very different from walking onward while conquering their own fears. That is why we give the act of walking onward a special name. We call it 'courage'."

- Aizen to Yhwach.

Trivia

 * Aizen can be compared to Christianity's Lucifer in various decrees: The first is that both originally served a greater power before acting on their own whims to take control of reality. The second connection is that they manipulate others, gathering armies to aid in their endeavorsand, being sealed away after the coup failed. Lastly, Aizen's final form resembles the humanoid version of Lucifer's Red Dragon form from the as  by.
 * The background music used in Aizen's final battle with Ichigo, Lucifer's Dance Parte B when he assumes his final form and Cometh the Hour Part A when sealed by Kisuke, are borrowed from the  movie.