If we had to describe Robert Gu when we first meet him in three words, we'd say "old," "poet," and "jerk." But at the end of the book, we're not so sure. Let's take it one-by-one:
Robert is seventy-five years old and, when we first meet him, he's just beginning his recovery from Alzheimer's (and old age more generally). He's in a wheelchair and he's very confused about the situation, which is why he continually confuses Miri and Cara in Chapter 2.
But when the doctors finish with him, he looks young—Juan says he looks about seventeen (4.123). He's also physically in good shape: he might even be in better shape than when he really was young. As he notes, he skips down four steps running down the stairs now, which he never would do when he was young (16.126). And when the Elder Cabal is breaking into the biotech lab, he's carrying one of the heavier packs because he's in better shape than the other oldsters in the Cabal (21.93).
So Robert starts out enfeebled but thanks to medical technology, he gets a second chance to be young—at least physically.
We hear a lot about how Robert Gu was a great poet back in the day. He wrote this really great poem sequence called Secrets of the Ages. Here's how good his poetry is: even the people who can't stand him know that it's good poetry. For instance, his ex-wife (who never has anything nice to say about him) says, "those poems are a work of genius" (13.109).
But when Robert comes back from the Alzheimer's, his poetry doesn't come back with him. As his body is getting better and better, Robert realizes that he just can't do the word-by-word part of poetry:
Yet none of these morning brainstorms contained poetical detail. He had the ideas. He had concepts down to the level of verse blocks. But he didn't have the words and phrases that made ideas into beauty. (3.108)
In other words, he can't write poetry any more. Robert hits his head against this limit a few times, though he seems to finally admit that he can't write by Chapter 7 (7.18). Rainbows End never entirely answers the question "Why can't Robert write?" Robert says the Alzheimer's cure destroyed his talent (35.18)—but it could just as easily have been the Alzheimer's itself that destroyed the poet part of his identity. This is a question about identity that we'll come back to in our third section.
Instead of poetry, Robert discovers he's now good at math and science-y stuff. Instead of waking up with insights about poetry, he wakes up with math proofs (3.109). He's not just good: he's—gasp!—interested in that stuff: "His subconscious had turned traitor, fascinated by how things worked, by technology and math" (3.109).
When he looks at something like Xiu Xiang's transport tray, he knows just how to make it do what he wants it to do (which, in that case, is mess up a car real bad) (8.83-114). At some point, he seems to start enjoying the science side of the world, which is why he lets Juan do the poetry part of their final composition project, while he tackles the math/computer side. As he tells Miri, he could be better at math… and it could be fun (19.111).
Now, since we are both poetry and science nerds here at Shmoop, we believe that Robert has transferred his love of poetry (all that beauty and truth) into his love of math (all that beauty and truth!). So Robert doesn't really change all that much here—he just shifts his love of beauty (poetry-style) to his love of beauty (math-style).
He truly grows to appreciates technology, describing how "the haptics flipped in coordination, never losing contact or slipping in a way different from the vision it was supporting" (Epilogue.22) in an almost poetic manner.
So, just like how he changes from old to young (sort of), he also shifts from poetry to math. He starts out talking about proving the doubters wrong about his poetic skill: "he would overleap them, to the sort of recognition he deserved." But he ends up doing math for a company and feeling good about being appreciated:
"For the first time since he lost his marbles, he was creating something that others valued." (35.31)
Huh. Is there a difference between Robert's desire for "recognition" for his poetry and his desire to be "valued" for his math skills?
Now whenever we say "jerk," feel free to fill in the four-letter word of your choosing, because, when we first meet him, Robert is such a colossal… jerk.
Both his ex-wife and his son note that Robert is not the kind of guy you call when you need a pick-me-up: Lena is very free in calling Robert a "monster" (12.78); while Bob wins for understatement of the year when he tells Miri that Robert Gu "is not necessarily a nice fellow" (7.43).
But even without those comments, we could see for ourselves that Robert starts out as a jerk. Mostly we get that through his jerky opinions. And he is not shy about sharing his opinions: his son's job—protecting the world—is a dead end gig (3.64); the medical assistant who carefully helps educate him has a "menial mind" (3.105); Louise Chumlig is a cretin (6.47); the other people at high school probably have a narrow viewpoint (3.111); etc. Etc. etc. etc. This goes on for a while. For a fun time, count how many times Robert calls people "subliterate" or "illiterate."
But eventually, Robert seems to lose his killer jerk instinct. It doesn't go quickly. It's not like he wakes up and says, "I'm a happy person, maybe I'll be nice to people now." At first he's not thrilled, noting that,
It was hard to dominate people when you didn't know what they were talking about. (3.76)
What a sweetheart, eh? He's sitting at dinner with his family and he's still thinking about how hard it is to dominate people. What the what?
But by the end of the book, Robert isn't so much a jerk anymore. We would ask him the same question that Sharif does at the end:
"What really changed in you? Were you a decent fellow from the time of your dementia cure?" Or was it some new experience? (35.25)
Because it's not really clear to us. Robert's brain does go through a pretty damaging tumbler cycle, so maybe it was the Alzheimer's. Or maybe it was the cure that changed him. But then again, he's still pretty mean after that, as when he tells Miri that she's a bossy, "fat, brainless brat" (7.30).
So maybe it's the experience that changes him from being a jerk: losing the foundations of his identity (mean literature professor) and having to rebuild himself to adapt to this new world. We mean, besides all the tech differences, this is a world where his son can scold him… so it's a big shock to him.
Again, we're not entirely sure what changes Robert's identity away from being a jerk. Only that, thanks to medical technology, he has a second chance and an opportunity to change his life.