I recently reread Sisters Grimm as an adult, and I can't stop thinking about how underused Mr. Sheepshank's three children were. They only appear as cameos after TUS (in fact, they're so insignificant that Buckley got Bella and Natalie mixed up in a later book).
Their entire world shifts completely in a single day. They lose the only parent they've ever known - and their minds are probably free from a lifetime of magical manipulation. They learn that many of the things their father told them were lies. They are sent to live with birth parents they've never met, who have ten years of hopes and expectations for them to live up to. They're separated from their adopted siblings for the first time. Two of them have to deal with the emotional aftermath of murdering someone at the age of eleven.
And then, just as they're unlearning a lifetime of violence, war breaks out, and they're on opposite sides - Bella and Toby with the resistance, and Natalie returning to the Hand.
