Trouble on Reserve can be found on Wattpad, which is were I read it. The author's note says the voice is different from her usual, but I didn't really notice. It was written for someone who might have never even heard of the Hollows before reading it. I can see how someone who's never read the Hollows could read it and not be completely lost, but I think some things would confuse them. If nothing else but not knowing who Trent and Rachel are.
Trouble on Reserve jumps straight into the action, with Rachel upset with Trent because he has her working for him as security while he's in a shady meeting. She was only meant to be security for a fundraiser, but things come up and she's (understandably) upset with him over it. Mostly becasue he didn't tell her anything about it. I found Rachel's standoff with Mr. Glock to be amusing and so very Rachel. The poor guy didn't know what to think about this 'arm candy' (she calls herself that) with a splat gun, which runs on compressed air and is untraceable (yeah, she lied about the second part, but he didn't need to know that).
After Rachel and Trent's disagreement (they have a lot of those in the books too) things quickly escalate into an assassination attempt with Rachel as the target, although Rachel at first assumes that the target is Trent (really, she should be use to people trying to kill her!). Trent shows himself willing to kill for her, although she stops him from killing the vampire, since she knows he doesn't want to be that man. Although it says a lot that he's willing to be that man anyway, to protect her.
I'm kind of glad that I read this after reading The Undead Pool, but it was kind of hard to see Rachel and Trent like this after seeing them in that book (trying not to spoil that book!). Trouble on Reserve is set between A Perfect Blood (#10) and Ever After (#11) - that's were FictFact puts it at least, although the author suggests reading it after Ever After, in case of spoilers. If nothing else, (assuming you haven't read it) read it before reading The Undead Pool, since it's very strange to see the difference in Rachel and Trent's relationship between Trouble on Reserve and The Undead Pool. Getting very close to spoilers, so I'm going to leave this here, before my review gets longer than the story it's reviewing!