It's Henry's movie, and for all his eccentricities and fixations and rages, he's a very conventional man.
Miserable and fiercely protective of it, Henry (Billy Crudup) is a children's book writer. His longtime relationship with illustrator Rudy (Tom Wilkinson) keeps him on something like an even keel. Given the difficulty of coming up with ideas for new and marketable kids' product, they like to work loosely -- finding inspiration in the least expected places. Or at least that's the impression you get from the opening scene of Dedication, in which they're in a theater watching a porn movie -- the mere fact that they seek out such entertainment/stimulation in a theater makes them seem quirky. "Oh god damn it, Henry, I think we've seen this one before," grumbles Rudy. And then Rudy hears what he needs to hear when an actress demands, "Touch my beaver."
A-ha! Rudy hustles his partner out of the theater, content.
It seems an ideal relationship. Rudy puts up with Henry's general grumpiness and self-absorption (close-ups of his repeated rearranging of items on diner tables suggest he's got control, OCD, and/or other anxiety issues). Henry is bemused by Rudy's working methods, takes his paternal advice to heart, and acts out occasionally in front of their patient and well-rewarded publisher, Arthur Planck (Bob Balaban). And Justin Theroux's directorial debut suggests he's got a sense of how time and subjectivity might be fractured on screen. Given his work as an actor with David Lynch, such an inclination may be predictable. It's also not surprising that, despite or because of Rudy's charm, it's Henry who provides the film's structure, his tense, angry, depressive sensibility that fractures it.
Henry's font of need is the film's point of departure. He looks to Rudy for answers, or more precisely, frequent conversation, concerning his grievances, for instance, that his most recent girlfriend has left him because he won't agree to marry her. Indeed, Henry's primary commitment -- his dedication, as the film's title has it -- lies with Rudy, the father he never had, the stable force in his otherwise chaotic emotional existence. But, as much as Henry means to cling to Rudy's bits of insight ("We communicate nowadays through damage," or "Finish the damn book," meaning Henry's "real" book, not the stories he writes for money), David Bromberg's script has something else in store for Henry. As Rudy puts it to him, "Find a nice girl."
This directive becomes too cute when Rudy discovers he has a brain tumor and dies, leaving Henry friendless and illustratorless. He continues to converse with Rudy throughout the film, in scenes that seem set in his head, but also seated on a sculpture of a globe, a neat metaphor for the world of pain in which Henry resides. The gimmick allows Henry to imagine himself in relation to someone else, even as he is clearly only interested in himself. You've surmised by now that he is unhealthy. "If you keep hanging around with you, you're gonna kill yourself," observes Rudy from his inside/outside, living/dead perspective.
Lucy (Mandy Moore), the nice girl, arrives pretty much on cue. (And we might take a moment to give thanks for all the imaginative, smart, supportive, loving girls available to broken men in recent movies, from Garden State to Lonesome Jim to The Bourne Ultimatum.) Because the beaver book has been a gigantic success, Arthur assesses that a sequel is in order. And so, following an appropriate period of mourning, he finds a replacement for Rudy and demands that Henry fulfill the terms of his contract by working with her -- and meet a deadline for a Christmas-themed story and holiday publication date. Henry, of course, hates Lucy on sight because she is not Rudy, and spends the rest of the film working out his many difficulties in relation to girls in general and Lucy in particular.
She brings a bit of baggage, such that she does live in scenes that do not involve Henry. She lives in a building owned by her mother, Carol (Dianne Wiest), who charges her rent and worries, loudly, about her career choice. She has an ex-boyfriend, Jeremy (Martin Freeman), a professor of English literature who was also her "adviser." His about-to-be-published academic tome will make him famous in certain circles, and he's decided he wants her, as he's reached the point in his life when a wife would be appropriate. Lucy, as quick and perceptive as she might appear to be, is just dumb when it comes to Jeremy, such that his offer of "security" resembles a means to independence from her mother, and, more importantly, to complication for Henry.
Though Henry tries very hard not to like Lucy, Dedication's generic demands soon overwhelm him. This means he must work through his particular specific emotional disorders, more or less one by one: he tends to say whatever comes into his mind, he's deathly afraid of cars, he hates the beach, etc. And so, a sequence of events leads him to reconsider what he says to Lucy, agree to ride in and eventually drive a car (imagine the hilarity of Henry wearing a bike helmet while inside the vehicle!), and spend time at the beach, seeking inspiration for the Christmas beaver story.
Henry even goes so far as to appreciate her appreciation for telescopes, which she explains thusly: "My brother used to have one of these. He used to think the universe was his personal property. I think most men feel that way." If Henry -- so willfully idiosyncratic, annoyed, and isolated -- doesn't understand himself as lumped in with "most men," you get the thumping point. So Mandy-Mooreishly sweet and generous, Lucy puts up with contrived coincidences and deliberate cruelties en route to her correct choice. If only she had known Rudy or -- better -- if only Dedication had known that it really is about Rudy and Henry, she might have avoided her all too conventional fate. But it's Henry's movie, and for all his eccentricities and fixations and rages, he's a very conventional man.