When we take a more in-depth look into this, we see that her feelings are a lot more complicated regarding their relationship. It is easy to mistake her actions towards Denji as an implication of love early on in the series.
She saves him from his miserable lifestyle, provides him with a job, takes him out on dates, and even lets him live with her at one point. Unfortunately, all the happiness in Denji’s life which was brought to him due to being saved by Makima is almost poetically snatched by her.
It turns out that everything she did from the start and all the fake affection she showed him was to eventually break him apart so that he would eventually completely submit to her and become her “dog”.
Why Did Makima Do All This for Denji?
The reason why she used and emotionally manipulated Denji to this extent is revealed later on in the manga. It turned out that the being Makima was infatuated with was not Denji but in fact, the entity inside him, Pochita, who is the Chainsaw Devil.
Makima is a huge admirer of Chainsaw Man and his power of being able to erase other devils. She wants to break the contract between Denji and Pochita so she can control the Chainsaw Devil. She claims that her goal is to create the ideal world without any fear, death, or tragedy and that the “Hero of Hell”, Chainsaw Man’s power would give her the ability to achieve this.
This would make her an omnipotent being who could control life and death based on her whims. Her admiration for Chainsaw Man however was even more than her desire to fulfill her goals since she explains that she would be satisfied even with failure as that would mean being eaten by him.