These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
YMMV: The School For Good And Evil
Darker and Edgier: The second book might as well be titled "Well, That Escalated Fast".
Evil Is Sexy: Subverted. Most of the Nevers would never count as Sexy from their descriptions. And Sophie loses any sex appeal she might have had as she fully embraces Evil.
Family-Unfriendly Aesop: The second book boils down to saying you can't love both a romantic interest and a friend, you have to choose one or the other.
Ho Yay: Tedros kisses Sophie...as she's disguised as a boy, and Tedros fully believes she's a boy.
Les Yay: Between Sophie and Agatha. It eventually blossoms into full on Foe Yay as Sophie accepts her role as a witch, and Agatha hers as a Princess, only to return to Les Yay as Sophie sacrifices herself to save Agatha, and the two are reunited and returned home.
Moral Event Horizon: Sophie first crosses this when she murders The Beast for cutting her hair. She does it again when she breaks her promise to Agatha to arrange to kiss Tedros, in favor of wanting to stay and try to become a Princess. She crosses it a final time when she arranges for Tedros to find Agatha, whom he loves, in her arms at the Evil Ball. Of course, how much of this was of her own volition is questionable as it's implied that some, if not all of her Evil behavior may be due to the Head Master's control of The Storian.
The Woobie: Dot. As a villain, she's got her work cut out for her. Her talent is turning things into chocolate. She gets kicked out of her room by Sophie, Hester, and Anadil. And even Agatha pulls her hair when she learns that Dot knows how Sophie and co. have been entering the school and defacing it.