If Bob is God, that makes Mr. B … what, exactly? We're never told exactly who he is, we don't even know his whole name, and apparently he has no job description. He's described as an "assistant, private secretary," and then later "more than a personal assistant, less than a father figure—a fixer, perhaps, facilitator, amanuensis" (2.3, 2.27).
Does that make anything clear? Not really. So, let's take a closer look.
Mr. B is every old serious mentor that you have ever seen rolled into one and projected onto an intergalactic scale. Think Giles from Buffy. (Or do like we did, and imagine all of Mr. B's lines in Giles' voice.)
Rosoff makes it pretty easy for us to see that Mr. B is an old-fashioned kind of guy. He wears "spectacles," not glasses (2.3). He eats "melted Gruyère on toast," drinks strong coffee, and writes on a desk that probably looks like this (17.6).
Seriously, who does that? (Well, Gruyère is pretty tasty. But still.)
All we know about Mr. B's background is how he is described when he applies for the job of God of Earth.
The only serious applicant, a middle-aged man known as candidate B, had a solid but unexciting record in middle management; when he appeared before the board to state his credentials, his quiet, somewhat professorial manner failed to generate enthusiasm. (3.3)
With that kind of description, it's not surprising that we almost always see him sitting at his fancy desk worrying about paperwork. This isn't the kind of guy who would invent the platypus or the hagfish. (Or, apparently, sex: when he realizes how Bob has managed animal reproduction, he "wants to tap the boy on the shoulder and say, 'Excuse my presumption, but are you quite certain about that?' [6.14].")
Mr. B doesn't become an interesting character until after he resigns from his position, because that's when he starts doubting himself—and doubts are always the interesting stuff. If he isn't Bob's lackey, what is he? Let's let him ask the questions:
What am I? he wonders. I am the one who bullies and prods, who cajoles and begs and pleads. I am the one with the files and the lists and the knowledge of life and death. I am the one who yanks Bob out of bed to do what needs to be done. I am the brain and the conscience of Bob; what is Bob without me? What am I without Bob, he wonders. (46.36)
These are big questions. Mr. B seems to have the sense that he's somehow incomplete without Bob—that, as irresponsible and dumb as Bob is, he brings something to the world that Mr. B could.
But we're not so sure about that. See, Mr. B loves Earth in a way that Bob never could. Sure, Bob loves some parts of Earth—the young, sexy, female parts. But Mr. B loves it all. He loves all the little people, and the animals, and especially his whales. He has a sudden brain flash:
I care about earth and all of Bob's tragic creations. I care about Estelle, and I care about Eck, he thought, though I cannot allow myself to think of him, for there is nothing I can do to reverse his fate. I care about Mona, despite a clear understanding of her faults.
And then a funny thought occurred to him, so funny that he began to laugh. And once he began laughing he could barely contain himself. How pathetic I am, he thought. I even care about Bob. (38.27)
Pathetic? We don't think so. In fact, this shows us that Mr. B is the selfless opposite of Bob. He doesn't give up on Bob because in his heart he truly believes that Bob can change—and that he can help him. It's no wonder he ends up with the job at the end.
Remember that we said that he has no job description? Well, in the end Mr. B just comes up with his own job description: God.
Mr. B is a quiet guy, so he probably just assumed that his job was to sit down and shut up. At the very end though, he makes this discovery, "It is he, not Bob, who cares for this world. Bob is not, and never has been, fit to rule. He is a cog. A boob. A cur. He is no God. If there even is such a thing as God, thinks Mr. B. If there is such a being, it cannot be Bob." (44.14) Okay, so, what does that mean about Mr. B if Bob is not God?
"He [Mr. B] hesitates, and all at once a realization explodes in his brain like a bomb. He groans, gripping the desk to avoid falling. Why has he never seen it before? The obviousness of it. With purest clarity he realizes that Bob is not the God to whom the multitudes direct their entreaties. Bob is not the all-merciful, the all-seeing, all-knowing deity of grace and wisdom and compassion. […] No. Bob is not God. He is." (44.19)
Ding, ding, ding! We have a winner!
Rosoff reveals her soft and squishy side by showing us that Bob was not the "real" God all along—and that maybe Mr. B wasn't either. God isn't a specific being so much as a job description, and more than one being can fill that job description.
Yeah, pretty heretical stuff. But Rosoff isn't knocking down the whole idea of a merciful God. Instead, she's asking how it could be that things on Earth can go so right and so tragically wrong. Her answer (which, let's remind you, is fiction) is this power struggle between an incompetent but brilliant teenager—and a competent but maybe not-so-brilliant grown-up. By introducing Mr. B alongside Bob, she explains the beauty, the horror, and the practicality of Earth's existence.
One final thing. Mr. B keeps knocking himself as being practical and maybe even a little boring, in contrast to the imaginative and brilliant Bob. But we have to say: whales. Anyone who could invent whales isn't nearly as boring as he thinks he is.