Conversed: Why do the women on these shows always seem to turn good?
Alice secretly betrays Charlie by rescuing Bob from death, but she makes to clear that she's True Neutral and if she ever sees Bob, she'll kill him. Then she leaves and is never seen again.
The second Arc comes, showing that she used Bob to kill Charlie, so she gains his fallen empire, becoming the new Big Bad.
Big Bad denies all women applying for his organization because of this trope, so he ends up with a reputation of a sexist, his mooks make jokes thinking he's a homosexual, and complain about lack of women around. The Big Bad himself dies as a virgin.
Reconstructed: The new Arc comes along, the villainess Darlene has Bob right where she wants him, but Alice makes a Big Damn Heroes moment, claiming that she'll hang around him for a while for entertainment. She becomes the one to kill off Darlene.