Aizen/Ichigo
Mostly just opinion so bare with me?
To begin, the relationship of a romantic nature between Sousuke Aizen and Ichigo Kurosaki is a crack pairing, but the general premise of it shouldn’t be ignored, since carnal feelings aside there is an anticipation for when the two met again. So if you’re a fan or just interested in how I’m planning to justify them, thank you for reading this.
Along with more textual examples, described later, there are some very artistic themes and images associated between the two, showing the likeness of characters and the compatibility of personalities. Starting off slow we’ve got a certain poetic symbolism with their swords, specifically in their names, Zangetsu and Kyoka Suigetsu. Going by the translations "Zangetsu" breaks down into "Cutting Moon" while "Kyoka Suigetsu" directly means "Mirror Flower Water Moon". Since Aizen’s sword is an illusionary one we can assume that it’s the flower being reflected in the mirror and the moon in the water, like some translations say. Isn’t it funny how the same moon that Ichigo’s sword aims to cut(repeated in his shikai attack "Getsuga Tensho" the Heaven Piercer) is reflected in water, one of the only things you can not divide with a blade? Flowers and Mirrors for later, the moon is constantly shown in the Bleach manga. Turn a page and there is a chance that the crescent moon’ll be hanging around somewhere, usually in dramatic scenes and everywhere outside of Las Noches.
Given that Aizen’s power is Complete Hypnosis, there is an emphasis on the sense of sight with him, oddly connected to Ichigo’s condition early in the manga. The first Volume Poem "We fear that which we can not see", in reference to the world of the dead and the hollows in the human world, is eerily brought up again 325 chapters later by Aizen, "The Betrayal you can see is trivial. What is truly fearsome, is the betrayal you don’t see, Captain Hirako." (-99, page 19). Does Ichigo innately understand what Aizen is trying to say? He’s been plotting the ascent to the throne for an unknown amount of time , all of it dealing between those that can see through him and those that can’t. Ichigo is alone in his world as the only person that can clearly interact with the dead(Karin not withstanding since she ignored it, and other sensitive beings since he was not in contact with them at the time). Essentially he is alone as a person who can see things that he shouldn’t be able to see but continues on it anyway. This is probably one of the definitive "otherings" that Ichigo thinks about for people, much like Aizen. Both of their social worlds are divided between who can see, who can understand, and who they actually trust (both lists are short).
Another volume poem that helps invoke an imagery between the two is Volume 12 Flower on the Precipice which reads, "We think a flower on a cliff is beautiful because we stop our feet at the cliff’s edge, unable to step out into the sky like that fearless flower" and without jokes, Ichigo and Aizen are both represented by that flower. The repeated notion that Aizen is trying to transcend what is it to be human, shinigami, and hollow as well as from guard, to lord, to God show only a reach and desire to be more than what he already is. He is a flower that really wants to bloom and grow in the sun. The flower on the cliff is named fearless something which, at least the out posted Arrancar, has been used to describe Aizen and explains why the weak feel pulled to him. Ichigo represents that daring attitude of the sassy flower that lives off of a cliff. Ichigo has a case of leaping before looking and falling from the highest of places. While reclaiming his shinigami powers what happens? He falls off of the edge of an apartment complex of his mind while in reality he’s trying to drive himself up a wall of rocks. During his fight with Byakuya where does it all take place? The cliff with the Sokyoku only this time he doesn’t fall from it but still flitters around as if he owned that spot. Even more recently against Ulquiorra, it might have no been a traditional sort of cliff but Ichigo is still fighting in the highest of places where most are unable to reach. Neither of them are too concerned about where the safety nets end and are comfortable with physical opposition always existing around them, like that flower deifying gravity.
The final bit of imagery between the two is a personal favorite of mine that rests on dependence. Although he’d called the King of the Soul Society, that being is their God in laymen terms, just with Aizen has set out to be. Ichigo has been called and referred to as the King of his own inner world. The two offer a monarchy and a theocracy, even if its only to themselves.
Now for the real stuff, as in some kind of factual evidence as to why the two could be a couple. As awesome as the ideas above were, they’re only symbolism working its magic when a story can tell something completely different. What is very supportive of this rather cracky coupling is the canon use of "interest". That is certainly the keyword for the couple. Aizen and Ichigo do not meet in person until the End of Hypnosis chapters, where they are adversaries, but that is not too difficult to imagine since until that point roughly 2/3 of the active storyline characters were considered to be Ichigo’s enemy. Aizen leaves after his First Exposition, which he did for no reason other than to clarify things for Ichigo, and mentions how he is an interesting person. Twenty chapters later, Captain Hitsugaya point black says to Ichigo that "Aizen is interested in you, Kurosaki Ichigo" (197, page 14). Three chapters before that Ulquiorra leaves the fight mentioning how he’ll "report to Captain Aizen that the ‘fake’ shinigami he is so interested in...is just a piece of trash...unworthy of his attention"(197, page 17).
It seems oddly definitive for a usually apathetic arrancar to say. We know that the hollows love and respect Aizen, even going a far to taunt the invaders just so they can beat them in top condition and reclaim their seat near Aizen (253-4). Did Ulquiorra think he had a reason to be nervous? Why, indeed, should one of Aizen’s most loyal knights feel anything definitive about an a human enemy. And on that note, what reason does Aizen have to send his elite just to evaluate the human ryoka? It is undisputable that Aizen certainly has an invested interest in Ichigo.
Next we have a visual clue as well as some dialogue. In Chapter 255, after dismissing Syazel (and questioning him on observations Ichigo) Aizen and Gin have a conversation.
Gin: ...seems you’re enjoin this an awful lot. Even though your subordinate got killed.
Aizen: ...is that how it appears?
Gin: Am I wrong? I wonder if you ain’t enjoin the fact them kids’re winnin’ and gettin closer to here. That’s the kind of face you’re makin.
Gin: Not at all. Strangly ‘nough, I’m feelin the same way(255, page 10-12).
And then it cuts to Ishida’s fight. For what reason is Ichigo’s image just placed there, when there are several other important characters to highlight? Is Ichigo once again being tied into an interest of Aizen’s and/or acting a foreshadowing of whatever amusement Aizen might have in the future. Visually the idea and image of Ichigo has been juxtaposed with "enjoyment".
During Aizen’s second exposition he explains his use of Orihime to lure the ryoka in, divide the power of the Gotei 13, and confirmed that he was going to destroy Karakura to make the royal key.
Obviously the "you" is the plural form but once again we have the mention of many and the possibility of other characters for emphasis, or not at all, and Ichigo appears again. Are still getting an emphasis on just main character/villain dichotomy or is this just an extension of interest and amusement that has been constantly mirrored against Ichigo.
It’s all been well and good but a one sided interest is cute, but the degree can be somewhat stalkerish. There has been another idea repeated by Aizen; Understanding. During his Thrid Exposition in the Turn Back the Pendulum Arc he says to Shiniji, "You never tried to get close to me. That’s why you didn’t notice that I had been replaced. I had the man who replaced me memorize my movements, and my response patterns towards the captains and other guards. If you had a thorough understanding of me, you might have noticed a slight difference in my movements and habits"(-99, page 9). It’s minor but Ichigo looks to be taking steps in understanding Aizen or at least his actions. He wonders aloud "We run and run but it doesn’t feel like we’re getting any closer...is that palace really there...? It’ not a mirage or something is it...?"(245, page 14). A mirage is just an illusion. Ichigo seems to be thinking about what Aizen might throw at them and tip toes closer to understanding. After all he was one of the few people there for a good part of Exposition One.
Like I said before, Aizen/Ichigo is a crack pairing with pretty much no chance of happening in the manga. That doesn’t mean that there aren’t compatible character interactions, moments, and philosophies that can’t link the two together. Even if the romantic part of all this is ignored it is hard to imagine that Aizen doesn’t have more plans in the future and if any of them involve Ichigo. Even if you don’t like the couple try to appreciate the dynamic that is possible between the two.