Urban fantasy fans will likely enjoy this LGBT take on the traditional urban fantasy forbidden romance, but personally, the tropes were played too straight for me to take the story seriously.
Syl Skye has the "different from other girls" attitude down to a tee, spending much of the book complaining about how her friends are mean girls and she's just too weird to fit in. Honestly, this trope is no fault of this book/author in particular, but it's just one I've long learned to be wary of. I've been in several schools in multiple countries myself and have yet to find an environment that actually supports the petty sniping that goes on with Syl, Fiann and the rest of the "squad", who for that matter don't behave like a squad at all and have the personalities of cardboard. I hate it when stories include girl-on-girl hate just because, especially if the protagonist acts like she's above it all while continuing to sling mud at her supposedly stuck-up rival.
Bear in mind that during this entire time, Syl is the Cinderellaest Cinderella who ever Cinderella'ed. Daddy's no longer sending her money so she's broke and can't go out for concerts and drinks with her douchebag "friends" anymore. What a horror. To add insult to injury, after she makes her friends, a party of at least five other people, wait for her for half an hour so that she can try in vain to meet up with her idol, they decide they're done and ditch her to catch the last train of the night home. What terrible friends. I mean, I was just kind of incredulous reading that. Sorry, but they indulged your obsession for 30 minutes (x 5 people = 2.5 hours wasted) and then do the smart thing and leave so that they can goddamn make it home, and you have the gall to frame it as their fault for being selfish bitches? Really?
Then, when you get down to the writing, Syl is simply annoying in that her voice reads like a ten-year-old on her first crush. An example:
'Ugh, no. She'd think I was out of my mind.
No, she wouldn't because...Because she felt it too, my heart whispers.
Stop it, heart, ya darn traitor!
Being obsessed and acting all crazy bananapants over a goth-rock star isn't my jam, no matter what passed between us in those few moments.'
...Inner Goddess, anyone? Bellastasia say hi.
By far the best parts of the novella are the scenes between Rouen/Euphoria and Agravaine. Those are the only times where there's conflict, both internal and external, that I feel like I should care about. Part of it is the darker, more earnest tone necessary for Rouen's situation, which I think Eldredge works much better with than the forced "fellow kids" style used for Syl. To be fair, if that style of writing doesn't bother you, Derailed as a whole probably won't. It does get bonus points for portraying lesbian heroines who stand up for themselves and their identities (yay!), but other than that it doesn't work as a piece of fiction.