Well, Cid Kagenou does reveal himself at a crucial point in the manga. This reveal has significant implications for the plot and character development.
I don't have a definite answer for you. The manga might be keeping us in suspense about who Cid Kagenou will end up with. It could be a surprise twist or a character that has been hinted at throughout the series.
In the light novel, Ayanokoji is clearly the more intelligent one. He has a unique ability to analyze situations and people's motives deeply. Ryuen often falls into Ayanokoji's traps because he doesn't fully understand Ayanokoji's true nature. Ayanokoji can anticipate Ryuen's moves and counter them effectively, while Ryuen struggles to keep up with Ayanokoji's complex thinking.
When Ayanokoji says 'I'll use any means necessary to achieve my goal', it reveals his somewhat ruthless side. He is not bound by conventional moralities when it comes to reaching his objectives. In the light novel, this could be a result of the cut - throat environment he is in. However, it also makes him a complex character as readers are left to question whether his actions are justifiable or not.
One of the notable quotes by Ayanokoji from the light novel could be 'I don't care about victory or defeat. What I want is absolute control.' This shows his unique mindset that is not focused on the typical goals of winning or losing but rather on having power and control over situations.