I'll start off -- I've been looking forward to talking about Firmin for a while, so let me spill my unorganized thoughts out here and hopefully get the conversation going.
It's been a while since I read FIRMIN -- as a bookseller I received an early galley copy, and I devoured it (ha!) right away. But my memory was jogged recently by reading Andrew Friedman's article "The Rodent Is Myself" in the August 2006 issue of The Believer. Friedman admirably traces the history of the rat/mouse in literature, from Dostoyevky's "mousehole" in NOTES FROM THE UNDERGROUND, to Haruki Murakami's character Rat and Easy Rawlins' fierce sidekick Mouse, through Art Spiegelman's MAUS and even Robert Sullivan's nonfiction RATS. His contention is that these novels and stories posit that either rats-are-like-humans (implying sympathy and even brotherhood with our fellow mammals) or humans-are-like-rats (hiding, furtive, urban survivalists), and that they all play with our fascination and disgust with our likeness to rodents.
But when he gets to FIRMIN, the most recent and the most literal of the literature of rodenthood, I feel Friedman stumbles. He writes "By collapsing the provocative ambiguity that shades MAUS into having a narrator who's simply a precocious rodent that speaks, the novel at times has a congenial, aw-shucks cuteness Firmin himself would loathe." I can't argue with the cuteness (which some of my coworkers found annoying, but which I think is part of Firmin's appeal, and his self-hatred and absurdity.) But the important mistake is:
Firmin doesn't talk.
Nor does he walk on his hind legs. Other than his ability to read, he's a realistic, garden-variety rat. I think the book's otherwise charming illustrations lead to this misapprehension (and the disconnect between image and text seems of a piece with Firmin's fantasies about himself), but the way I read it, nowhere in the text of the novel is it stated or implied that Firmin is a Mickey-style humanoid rat. He's the same kind we see scuttling in subways and basements.
And that's the tragedy that makes him all the more human -- makes him, in fact, an Everyman (or a Fur Man). His mind is full of thoughts, ideas, images, stories, fantasies, desires, but he is utterly unable to communicate them to his fellow rats (who don't care) or humans (to whom he cannot speak). His inability to communicate makes him utterly isolated, alone with his thoughts; no matter how much affection his human friend, Jerry Magoon, has for him, there's no way they can really understand each other. (He attempts desperately to break out of this isolation by communicating, leading to the funniest scene in the novel, when he jumps out of the bushes and frantically signs "goodbye zipper" to passersby, before realizing the futility and ridiculousness of the gesture). Firmin is us, not necessarily in his surreptitious garbage-feeding ways, but in his aching desire to communicate, and in his isolation when he is unable to do so.
But that's just my opinion. Agree, disagree?