It is likely a good thing this series started out with Verity. I'm not sure I would have continued beyond the first book if either of her siblings had starred.
Antimony... someone said they liked her better in this than in the short stories that I was blissfully unaware existed. What's the issue? oh, imagine Anakin with Obi-Wan's personality...plus Anakin's attitude problem. Deep down, she resents her family's need to hide, yet she uses it as an excuse to hide. Playing by the rules, she calls it. She can't admit she resents her whole family though, so she focuses on Verity entirely too much. Her internal monologues on Verity almost invariably include the word "selfish", multiple times. And...she makes it all about her.
She's never done serious fieldwork - has avoided it as much as possible in fact. So they send her on an undercover assignment based on her not looking like the rest of them. It mostly works - the heir apparent does figure things out but sits on his knowledge. He tells her as much at the end. She gets sent on a field assignment to a carnival, manages to get a job and get people to sort of trust her, wants actually to join it for real (see family resentment), and her handlers nix that thought by planning a purge. The owner's grandson is with her when she runs into someone who recognizes her, so she has to come clean and manages to get everyone to evacuate.
So...between her lack of experience in this sort of thing - when you run into trouble, backup is USEFUL, yet she didn't really keep her family up to date so they could assist - and her inability to do anything without thinking of how selfish her sister was to not play by the rules, be they form while doing acrobatics or well...keeping her head down...
She irritated me. At the point where the grandson, after hearing the acquaintance with a grievance and her innuendoes, left her to walk back - a part I would normally be feeling sorry for the h and thinking he was a jerk - I kinda was...well, what did you expect dummy?
The end features her wandering around far from home - doing exactly what the heir apparent intended I suspect. She isolated herself for her family's protection and that never goes well. And...she's also not thinking far ahead - her grandmother travels between dimensions. Don't think they can track her that way.