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.
Evil Versus Evil: Arguably Silarial is just as evil, if not more, than her twin Nicnevin.
Silarial comes off as the good one but when the reader gets a good look into her it's easy to see she's the worst of two evils when compared to Nicnevin, who while not thrilled about the truce between the courts, is content with it nonetheless. Compared to Silarial who not only wants Nicnevin dead and wants to take the Unseelie court, but wants to destroy it and all the fey part of it, and is willing to sacrifice any and all of her faeries to do so, Nicnevin seems like a saint.
Silarial allows the (almost) sacrifice of one of her changelings, trades off her best knight/lover to be tortured by her sister, and was willing to sacrifice one of her hand maidens for a chance of getting the Unseelie court.
Fridge Brilliance: Luis being gay completely explains all the times in Valiant when he ignored Lolli and why he never acknowledged her advances when she came on to him, despite being a depraved teenage boy and her being good-looking and willing.
Self-Fanservice: Ravus gets this a LOT. In the book, he was described as ugly and monstrous-looking (but having nice golden eyes). However, as Ravus warmed up to Val, he was shown to be a relatively okay guy with an extensive tragic backstory, (which he explains while he makes Val hot chocolate) making him wary of humans and fair folk alike. Top this with his poetic speech and deep voice, and it's easy to understand why many readers picture him as conventionally handsome before they've even finished the book.
Squick: Val letting Dave sleep with her, while Val was glamoured to look like Lolli and Dave was glamoured to look like Ravus. Especially since Dave starts undressing her while she's still asleep.