The original screenplay of Taxi Driver by Paul Schrader diverges from the movie in several important ways. In many ways it is the same, but the elements that Scorsese changed have made a world of difference.
Some of the essential dialogue made it to the movie unchanged. Some of it was re-written during rehearsal and production. By essential dialogue I mean the lines you remember. And poor Paul Schrader did not write the, "You talkin' to me?" scene. Scorsese and DeNiro cooked that one up between them.
The movie begins with Travis' eyes as he watches the road and the "scum and filth" of New York. The script begins with a long essay on who and what Travis is. "He has the smell of sex about him," Schrader writes. "As the earth moves toward the sun, Travis Bickle moves toward violence."
The movie opens on Travis' eyes, but from the way the lights move over his face, it seems that he's already in the Taxi. Then we see the taxi. I described it as being "like some modern-day dragon coming out of its lair." In Scorsese's world, the power of the Taxi is as important as whatever power is moving Travis toward his destiny.
Schrader moves from Travis applying for the job to Travis on the job. Scorsese moved from Travis applying for the job to Travis at home, writing in his diary. This is the main difference in the two stories. Shrader described one sequence of events. Scorsese used most of those same events, but switched the order in which he presented them. Shrader didn't show us Travis' apartment until after he'd been on the job a while. Scorsese showed us right away that Travis writes in a diary, otherwise his voice over wouldn't have had a logical source.
Schrader told us that the voice over is a diary. Scorsese was able to use images to show us the diary.
During the set-up section, Schrader included a few scenes about the life of a Taxi Driver that Scorsese cut, probably to get the story going faster. The pills and the booze are the same. Schrader's description of the wardrobe was used, right down to the white shirt with the cut-off sleeve. The scene with the counter-girl in the porno theater was longer in the movie, probably to give Diahnne Abbott more lines.
The first really important change is that Schrader introduces us to Betsy BEFORE Travis sees her. His script constantly tells us that this is what Travis sees and what Travis feels, but for some reason he introduced Betsy as if her own story has a life of its own. Cybill Shepherd gave Betsy a wonderful character and empathy and depth, but Betsy has never had her own story. She is and always has been Travis' dream woman. So Scorsese let Travis see her before he introduced what kind of person she is.
Schrader describes Betsy as a "star-fucker of the highest order." She is looking for "extraordinary qualities" in men. That's probably how men see it, but what's really happening in a woman's mind is that she's looking for somebody who won't treat her badly or take advantage of her. We know what men want, but we don't want to give it up to just anybody.
It's interesting to look at how Betsy and Travis feel about each other from these two points of view, mine and the author's. I said, "I have to give Betsy credit. She has so much self-confidence that she allows him to take the relationship further and agrees to see a movie with him." Schrader describes Betsy as realizing that "Travis' presence has a definite sexual charge. He has those star qualities Betsy looks for."
When he smiles, "…his whole face glows," and, "Betsy is completely disarmed."
Bobby DeNiro did have a charming smile when he was young, and he used it in all the same places that Schrader asked for it, but I'd really like to know if there was any discussion between Shepherd, Schrader, DeNiro, and Scorsese about the disparity between Schrader's vision of Betsy and what Shepherd knew about women because she was one. She plays Betsy as demure, but not exactly shy, and self-confident without being overbearing about it. I did not see any quality in her that I'd call "star-fucker," but maybe that's how the guys saw her.
Schrader did specify that Betsy went into the porno theater and stayed longer than she wanted because she was raised to be a good girl and not to offend her dates. I can totally buy this interpretation.
So in some ways I think he missed capturing real feminine qualities in Betsy and just described what he knew of women from observation, and in some ways he managed to get inside her head.
Schrader also wrote many of the original lines of dialogue between Travis and Betsy: when she compares him to that song by Kris Kristofferson, when he writes that he forgot to ask her last name. "Damn. I've got to remember stuff like that."
DeNiro, under Scorsese's direction, actually played Travis as far more sinister than Schrader wrote him. DeNiro tells Shepherd that he sees her as being just as isolated as he feels. Schrader wrote a couple of pages of conversation that might have been lifted from any cocktail party and told us about as much. The closest Schrader came to DeNiro's creepy intensity is this: "I watch you sitting here at this big long desk with these telephones, and I say to myself, that's a lonely girl. She needs a friend. And I'm gonna be her friend."
DeNiro and Scorsese followed that up with his creepy declaration at the diner about how he feels a connection between them.
Shrader put the desk and the phones in dialogue. Scorsese removed that dialogue and showed us Travis' hand as he moved it over the phones.
During Travis' courtship of Betsy, Senator Palantine takes a ride in Travis' cab and Travis goes into a rant about the filth in the city and how the stench gives him a headache. This scene went to the movie pretty much unchanged.
In the script we meet the other cabbies before we meet Betsy and we don't meet Iris until after the crazy husband who wants to shoot his wife's pussy with a .44 magnum and the scene where Travis buys the guns. Scorsese moved both the introduction of Betsy and that of Iris up in the timeline of the story, which gave their presence more weight in Travis' life. In fact, in the movie, Travis meets Iris before he takes Betsy to the porn theater. In the script, he doesn't meet her until he's well into his violent fantasies and obsessions.
It is here in the movie that Iris appears, but in the script it doesn't happen until later.