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.
Funny Moments: Several of Gemma's snarky inner monologues, and translations of what people say to what they actually mean.
Les Yay: There's already canon lesbianism, but given that most of the major characters are female (and often really good friends with each other), there's no way these books wouldn't be rife with this. Name two female characters, any two female characters, and you can probably make a pretty good argument for it, especially if Gemma is involved.
Not to mention the part in the first book after the girls get drunk for the first time. Felicity seemed really happy to show Ann how to "be intimate", complete with pulling one of the sleeves of her dress down to the point of seeing her..cleavage.
This is also used in-universe: when reading about Mary and Sarah, the girls immediately wonder if their unusually close friendship is actually a cover for them being "Sapphists" (lesbians).
In The Sweet Far Thing, Gemma finally confronts the Rakshana when they threaten to kill her brother. She quickly demonstrates whata badideathis is.
In Rebel Angels, Gemma & Co. are cornered by the Poppy Warriors, and the leader is teasing Felicity about her father raping her as a child in attempt to torment her into suicide. Not only does Felicity not give in, she shoots him through the throat, facilitating their escape, and later shows signs of beginning to overcome her shame and guilt and accept that she is not to blame for what happened to her.
"He shouldn't have said those things to me," she says in great hiccuping cries. "He shouldn't have said them."
It takes me a moment to realize that she is talking about Azrael and what happened in the catacombs. I think of her standing on that rock, piercing our tormentor with her arrow. "You mustn't be sorry for what you did."
She looks into my face, her sobs subsiding to a cold, tearless fury. She hoists the nearly empty quiver onto her shoulder. "I'm not."
Impossible to forget the hilarious scene when Felicity causes Lady Denby to loudly break wind after harassing Ann in Rebel Angels
Nightmare Fuel: Plenty of it dispersed throughout the three novels, including but not limited to some of Gemma's visions (especially in Rebel Angels), the Poppy Warriors, the water nymphs, and some of the more supernatural nighttime occurances at Spence.
Some Anvils Need to Be Dropped: Felicity's "ghost story" about the lives that await her, Gemma, Pippa, and Ann if they accept their roles as Victorian women is not subtle in its feminist message, but it's no less effective for that.
Tear Jerker: The scene in which Gemma realizes that Felicity was abused as a child, particularly when she warns Polly to always lock her door at night.