Raymond Babbitt is described as an "autistic savant," and Rain Man portrays him as being super challenged in terms of expressing himself and relating to others. Of course, one of the big ironies of the film is that his brother, who's not autistic, is actually just as challenged (if not more so) in terms of expressing his feelings—which we realize early on, when Charlie's girlfriend complains that he never tells her important stuff.
Through their relationship, though, both the brothers seem to grow and get a little bit better at connecting with others—which is really the big "win" or emotional payoff for the film.
Even though Charlie starts out viewing Ray as the one who is "disabled," Charlie's crummy interpersonal skills and bad, money-grubbing attitude show us that he's really just as challenged as Ray in communicating/interacting with the world around him—if not more so.
By learning how to help and deal with Raymond's unique needs and communication issues, Charlie manages to pull his head out of, er, the sand and work on his own communication problems.
Rain Man is all about family drama. Pretty much right off the bat, we learn that Charlie had a crummy relationship with his father and hadn't spoken to him since he was a teenager, and his mother died when he was two. Then, after his father dies and he learns that he's been largely cut out of his father's will, Charlie learns that he has an older brother—one who's inherited all of their father's cash.
Ever the selfish yuppie, Charlie sees an opportunity to get the money by kidnapping Ray.
Doesn't exactly sound like the recipe for a heartwarming story, right? Well, not so fast—Charlie and Ray's travels together end up bringing them closer together. D'awwww.
You know that saying about how if you love something, you'll set it free? Well, that's how we know that Charlie has truly learned to love Ray as his brother (as opposed to a bargaining chip)—he lets him go back to Wallbrook to ensure all his needs are met.
The ending undermines the whole movie. If Charlie and Ray had really bonded, and Charlie had really changed, he would have made the effort to keep the only family he had left closer.
Charlie's a big believer in that truism that money makes the world go around. At the beginning of Rain Man, it's pretty much all he can think about—largely because he's in some serious financial difficulties, of course.
Then, to increase his obsession with $$$, his father dies and cuts him out of the financial part of the estate. The solution to both problems? Kidnapping his brother, Raymond, who did receive the balance of their father's fortune, and holding him for ransom until the estate's trustee pays him out his half.
Luckily, Charlie learns not to be such a heartless bloodsucker by the end and puts Ray before his own greed… but not before Raymond wins a ton of cash for him in Vegas.
The ending reaffirms that money—not family—is really the main focus; Charlie and Ray only really bond after Ray gets Charlie what he's valued most in the world up to this point: money.
Sure, the "happy ending" involves Charlie getting the money he so desperately needed/wanted at the beginning, but the message is still that family is still the foundation of all other happiness—you need that before you can hope for anything else.
Okay, so this isn't a super obvious theme in Rain Man—Charlie doesn't seem to feel much of anything for most of it—but if you look a little closer, you can see a whole ocean of guilty, not-so-good feelings and history running under the surface of the Babbitt family.
Charlie starts out taking basically zero blame or responsibility for the problems he and his dad had, but by he end he's freely admitting that the breach was really his fault—a huge step in his character development, if you ask us.
Also, there's some painful history surrounding the family's decision to put Ray in Wallbrook. It seems that there was some accident or near accident involving Charlie, Ray, and a bathtub. Ray remembers the incident and, despite not seeming like a super emotional guy about anything other than routines/the breaking of routines, he gets upset remembering that he almost hurt Charlie.
By cutting Charlie out of the will financially and sticking the knife in further by leaving him the car that busted up their relationship, Charlie's father tipped us off that he was far from "forgiving" Charlie.
Charlie's father's will was a sly/twisty attempt at getting Ray and Charlie reunited (without letting on that's what he was doing) in order to help heal all the wounds of the past.