Changez finds his identity over the course of the novel because his final incarnation seems to be the one with which he feels the most comfortable, the one that feels the most genuine to him. Throughout the book, Changez gradually defines his own identity more and more against, or in opposition to, an American identity. Instead of continuing to think of America as a land of opportunity or as "a dream come true," as he did when he first arrived at Princeton, he begins to become aware of and irritated by the "American undercurrent of condescension" with which he is treated. When he travels to the Philippines, Changez notices the obvious dislike of a local driver, and he begins to feel as though he is "play-acting when in reality [he] ought to be making [his] way home, like the people on the street outside." He looks at his colleague's blond hair and blue eyes and realizes how completely "foreign" to him this man looks.

Soon, Changez realizes that the pleasure he feels when 9/11 occurs further differentiates him from his friends and associates, and he feels it because he "was caught up in the symbolism of it all, the fact that someone had so visibly brought America to her knees." The more of American life he witnesses, especially post-9/11, the less he likes it. He says,

America was gripped by a growing and self-righteous rage in those weeks of September and October . . . ; the mighty host I had expected of [America] was duly raised and dispatched—but homeward, towards my family in Pakistan.

His resentment of America begins to build. It grows when he is called a "[expletive] Arab" and almost engages in a physical and violent altercation with his attacker. Soon, his beard becomes, to him, a protest on his part, "a symbol of [his] identity," and he no longer wishes to "blend in with . . . [his] coworkers." Little by little, Changez finds more and more to dislike, more and more with which to be angry in America, and by the time he leaves the country, he realizes that "the lives of those of us who lived in lands in which such [terrorist] killers also lived had no meaning except as collateral damage." When he realizes that finance is how America asserts its control, he no longer wishes to be a part of the financial world; he goes home to Pakistan and takes a job at a university, making "it [his] mission on campus to advocate a disengagement from [the United States] by Pakistan."

Over the course of the novel, then, Changez seems to define himself, bit by bit, in opposition to those aspects of America that he begins to hate, personally and then professionally. He gradually comes into his own identity by the book's end.

Identity is not something fixed once and for all, but rather in a state of flux. This aspect is well illustrated in The Reluctant Fundamentalist as the character of Changez (whose very name implies change) takes on different identities throughout the novel, rather than simply losing or acquiring a given one. He first becomes the quintessentially-American success immigrant story, believing in the corporate ethos of meritocracy, only to reject this condition and adopt Islamic fundamentalism. When Erica is unable to have sex with him because of her inability to forget her deceased boyfriend, Changez asks her to pretend he is him and they finally make love:

It was as though we were under a spell, transported to a world where I was Chris and she was with Chris, and we made love with a physical intimacy that Erica and I had never enjoyed (p. 120 Penguin books paperback edition)

When Changez goes back to Pakistan for Christmas in Chapter 9, although his transition to fundamentalism has already become, he still detects "the Americanness" of his own gaze in looking upon his country of birth (p. 140). He is ashamed of the place where he comes from as "it smacked of lowliness" and becomes aware that he has changed (p.141). However, as he goes back to the U.S., he is unable to leave Pakistan behind and begins to grow a beard as a sign of personal difference. He also starts to neglect his work as he is absorbed in the increasing deterioration of diplomatic relationships between India and Pakistan and what looks like an inevitable war. He is particularly upset by America's

strict neutrality between the two potential combatants, a position that favored, of course, the larger and - at that moment in history - the more belligerent of them (p.163)

This leads Changez to find a common identity with those America has exercised a strict control on such as Chile where he is sent off to evaluate a publishing house in Valparaiso. In the course of this task, Changez becomes aware that he is, in a way, fighting his own people. He then decides to resign his American identity and take on that of the fighter for the rights of his native country.

Does Changez's shifting identity create tension in The Reluctant Fundamentalist?

I think that Changez's shifting identity does cause tension in the novel.  On one level, it causes tension between Changez no longer accepts what was once easily accepted.  His colleagues at Underwood- Samson are hostile towards his change.  Even Jim, who tries to help Changez at nearly every turn, cannot stand by him fully when the change impacts his work at the firm.  Changez's shifting identity causes tension as it marks a change from when he was a "happy go lucky," chap that aimed to please everyone as an outsider would.  The change from this to the beard growing, increasingly antagonistic individual helps to bring about tension in Changez and the world around him.

On another level, I think that Changez's shifting identity helps to provoke some level of tension in the reader.  The reader finds themselves having to confront some significant issues about fundamentalism in seeing Changez's shift in identity.  Perhaps, this shift is understood on the reader's part.  An equally valid response would be to reject it, seeing it as being disloyal to a country that gave Changez an opportunity.  This contrast in the reader's part is another instance where Changez's shifting identity helps to create tension.