Names are super important in this book. First, three of our main characters have legally changed their names: most important, Paul Delmonte has become Adam Farmer. The change in names implies a change of identity – more on that in the "Themes: Identity" section.
And how about the names themselves? They tell us a lot about the characters. Adam's dad is quick to point out the symbolic importance of Adam's new name: "Look at the name they selected for you – Adam. [...] Adam: new birth, first man" (23.22). This is true in terms of Adam's new birth under the Witness Re-Establishment Program, and it later speaks to his amnesia: every bike ride Adam takes is the first for him; every day is a new birth. Also, remember when biblical Adam ate the fruit and went from blissful ignorance to the acquisition of forbidden knowledge? Adam Farmer learns some forbidden knowledge too.
Then, of course, there's Mr. Grey. This is classic chicken-and-egg: which came first, the grayness of the man or the name? We can't be sure, especially because we don't even know if this is his real name (he also goes by Thompson). What we do know is that he really embodies his name; as Adam describes him:
[T]here was something – gray about him. His hair was gray. But more than that: to me, gray is a nothing color and that's how Mr. Grey seemed to me. Like nothing. (22.1)
While characters in this book are only explicitly described through Adam's eyes, their actions speak loud and clear for themselves. For example, the sacrifice Adam's dad made – risking his life and that of his family in order to reveal government corruption – shows that he is a man of integrity and honor. And of course, his decision to relocate his family, which meant giving up his beloved career and hometown, was another sacrifice, meant to protect the people he loved.
The fact that the author uses actions to paint characters makes it all the more difficult to understand the characters who don't really do anything. Brint, for example. He just talks, he never does. Even trickier to figure out is Mr. Grey. At the end of the book (spoiler alert!) someone drives a car into the Farmer family, killing Adam's mom. It might have been Mr. Grey, but we don't know. And because we don't know what this man did (or didn't do), we can't say for sure whether he's a good guy or a bad guy.
Luckily, we have another tool of characterization that makes up for someone like Brint's lack of action: speech and dialogue. Brint asks a lot of questions, and the impatience and insistence with which he asks them shows that he is trying in some way to manipulate Adam. Until the end, we're not sure exactly what information he's trying to get from him, but it's clear that he's fishing for something.
Adam's mom, another character who doesn't do too much in the book, is also characterized by her speech. What stands out to us is the way she so often directly addresses her family members (e.g. "That's the trouble, Adam" [26.15]). She does the same thing with her husband and sister. If you think about it, using someone's name like that when you talk to them isn't all that common. It almost always conveys a feeling of love and care, which Adam's mom is filled with. She also says things like "Now, now," (2.2) – you know, the kind of expression you hate when your mom says to you. It's endearing here though, right?