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 common character paired with Vergil is Dante. Some fanfictions explore a romantic relationship between them, which often delves into the complex dynamic of their brotherly bond and how it could transform into something more. It's a very unique take on their relationship.
Nero is also a popular character to be paired with the reborn as Vergil. Given Nero's connection to Vergil in the original story, in fanfiction, their interactions can range from mentorship - where Vergil helps Nero master his powers, to more adversarial relationships if the reborn Vergil has different motives.
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.
I don't know for sure. The ending of such a manga can be quite unpredictable and might not have been revealed yet. You could try discussing it with other fans to get their speculations.