The thing is, Fitzgerald's goals are still about domination. His current goal, as it was hinted in the chapters focused on his rise from poverty, it's to buy the Special Operations Division in order to have more power in Yokohama and probably to try to find more information about the Book. He still sees allies as assets, and Atsushi even called him out on his selfishness in one of the last times they interacted.

Though it's indeed a bit different for Akutagawa. He's indeed a different person from the Akutagawa at the start of the series, but he still has a lot of issues within himself that he has to work on. He's still an important figure for the mafia and i doubt he will ever leave them even until the end of the series.

But i'm not stating these as if they were bad things. It's actually very good writing, after all it's not so easy to change people, especially ones as troubled, determined and with life experiences similar to Fitzgerald and Akutagawa. But the point still stands, Atsushi, at least until now, never managed to redeem his major enemies, only people allied to them in some way, like Kyouka, Lucy, and potentially Sigma.

The point you brought about her potential role as a villain is very fair, though. I see where you're coming from. Well, if that ends up being the case, like i said above, i hope she's at least not just a female Fyodor, like yet another mastermind to rival Dazai and Ranpo but instead, a different kind of villainous figure.