One thing I don’t think people understand enough about Akechi is that he doesn’t like murdering.
Many Persona 5 Royal players, including fans of Akechi, are fooled by his mask in the Engine Room or in the Third Semester; they come to believe that this performance is his true self and thus that Akechi is a hash-slinging slasher of a man (see another post of mine for a more in-depth analysis of this mask).
But the truth, I believe, is the opposite. Akechi resigns himself to murdering, sure—believing that it is his key to killing Shido and being useful—but he doesn't particularly enjoy it (there are some caveats to this that I'll get to a little later, just bear with me please). More specifically, he wants to stop. This is the important distinction that I think most people don't make.
Akechi regrets where things are and the path he believes he's been forced to choose, asking "why couldn't [Joker and I] have met a few years earlier [so I could have a relationship like that to give me purpose]?" The game outright acknowledges this, actually, with Akechi's confidant ranking up to 9 through Joker thinking something along the lines of "it seems Akechi really regrets how things turned out." His motivation for killing is not (purely) out of an urge to harm or to feel powerful, but instead a pill he's forced himself to swallow in the name of revenge.
Now, let's compare this sentiment to another persona killer with a "o" sound in his two-syllable first name and a two-syllable last name that starts with "a" and ends in "chi"—Torhu Adachi. I should acknowledge now that I haven't actually played Persona 4. Any understanding of Adachi's character comes from hearing it described by other people and a little bit of research on the wiki. If I am wrong about anything, please correct me. Adachi's murders differ significantly from Akechi's because of the intent behind them. Adachi feels no remorse or regret for the situation; he kills because he is stricken with nihilism and boredom, drawn to the theft of life because it alleviates these things.
Akechi's sense of remorse is extremely dampened by his own dissociative tendencies—to the point where he actually very temporarily argues that his murders could be likened to the work of the Phantom Thieves and that he was "cleaning up trash"—but he does feel remorse. This is in direct contrast to Adachi's complete lack of empathy. Akechi's own justifications for why he kills are weak and he knows it. They are guards he puts up because they help him ignore exactly how fucked his situation is and how much he blames himself. He never brings that idea of being like the Phantom Thieves up again, even in the Third Semester. That could be because Atlus forgot about it (I wouldn't put it past them), but I prefer to think it's because he and Joker both simply know that it's not true.
So, that leaves us with the question of why Akechi kills. I think the answer to this is extremely obvious. He kills because he's being manipulated into killing. I have written so many essays on how Shido is actively manipulating and grooming Akechi into killing and I will likely write more. For now, though, all I will say is that Akechi was a child when he met Shido and offered himself as a weapon. He was then a child for multiple years after that point, always working under Shido. And while most fifteen year olds should probably know not to murder people, they are still fifteen year olds who can be manipulated into doing things they know they shouldn't do.
Akechi's relationship with Shido is similar to a child drug addict and their extremely corporate plug. Akechi knows the drugs are bad, but the reward he gets for doing them is so unignorably good (praise from Shido; feeling useful; feeling needed) that he cannot stop. Shido knows that Akechi is an addict in an extremely vulnerable position, and capitalizes on that for the purpose of extracting as much profit as possible.
It's here that I want to bring up those caveats that I mentioned before. When I say that "Akechi doesn't particularly enjoy murdering," you may hear alarm bells ring. Because, as I just described, he does get quite a lot out of this. I don't think it is fair to deny that; Akechi is rewarded for his murders. Not only is he praised by Shido and feels like he could be worth loving for the only time in his life, but he also gets a sense of control that the lacks elsewhere. Akechi's entire life, in fact, is defined by a lack of control and a lack of agency (see my essay on Akechi's agency and on my feelings about Maruki), and so the opportunity to exert his own control over people must be intoxicating. In my opinion, it is completely undeniable that Akechi is a sadist (and probably a masochist too but that doesn't matter right now).
That all being said, though, I think it's equally important to acknowledge how Akechi copes with having this need for control and praise. Because the truth is, the praise and control felt from murdering people is an unintended, likely unwanted side-effect. Unlike Adachi, Akechi doesn't kill for the rush or for the feeling it gives him. He kills for the sole purpose of proving himself invaluable to Shido and because he's being manipulated into doing it. I say "unwanted" because I imagine that feeling of pleasure must've actually clashed extremely powerfully against Akechi's own sense of remorse and his latent desire to be a hero (as seen in Proof of Justice and Akechi's confidant). But, as a child, he is unequipped to deal with the power and allure of these self-indulgent desires. They are likely literally altering his brain chemistry. Additionally, Akechi has and uses other coping mechanisms to feed his need for praise and control. He's already outright manipulative and often times mean. While these coping mechanisms aren't great and are still destructive, they are a hell of a lot better than murder. This is all to say that Akechi neither needs or enjoys the feelings of pleasure he gets from murder. He is not motivated by a selfish desire to see these needs met, but instead by a wicked adult playing with his underdeveloped mind.
In the end, I think that reading Akechi as someone who enjoys the murders he commits is a fundemental misunderstanding of his character. That's not to say he finds no pleasure in them or that he is completely disgusted with every kill he commits, but it is to say that his character shouldn't be whittled down to a low affective-empathy murderer like Adachi. Akechi's mask in the third semester is specifically crafted to have this effect, to shirk sympathy off of him and to make his wound seem less important than it is. In seeing through that mask, then, we acknowledge that he was hurt and groomed in a way that he cannot yet do himself.
