With so many complex and interesting characters in Atonement, this post could go on forever, so I am going to focus on Briony, because of her various and contrasting validations for existence throughout the novel.
I would like to start out by saying that I related to Briony throughout the first part of this novel in many ways. I myself have experienced the intense and difficult emotional transition from "childhood" to something beyond it. I also share her passion for writing and her desire to find a real life experience to bring truth to her works. I found this passage extremely revealing:
"She severed the sickly dependency of infancy and early childhood,
the schoolgirl eager to show off and be praised, and the eleven-
year-old's silly pride in her first stories and her reliance on her
mother's good opinion"(McEwan 70).
This passage strikes me because it reveals Briony great desire not only to seem mature but to actually become mature. Before this point in the novel, Briony's validation for existence was praise from others, "her mother's good opinion," and the childhood notion that no one was as "valuable to [himself] as Briony was" (34). As Briony's play falls to pieces, her validation for existence switches to an ability to write the truth, to be independent, and to abandon any childish dependency on her mother. This seemingly innocuous transformation , in my opinion, actually makes her eventual accusation a little easier to comprehend. I feel as though she does not accuse Robbie for the limelight it will bring her as much as she does it in the name of truth - that enigmatic entity she has decided she must discover in order to no longer be considered a "child." Though this does not completely rid her of guilt, I feel like it replaces any malicious intent with a complex emotional response to this difficult transformation from child to adult.
Additionally, I find Briony's validation for existence very interesting in the later half of the novel. Most people would automatically say that her validation is the possibility of atonement. Throughout the time that Briony was a nurse, I found her validation to be not so much a desire for atonement as an attempt to isolate herself from any intimate relationships with other people, thereby keeping her volatile imagination from destroying yet another life.
"Sometimes, when a soldier Briony was looking after was in great pain,
she was touched by an impersonal tenderness that detached her from
the suffering, so that she was able to do her work efficiently and
without horror... She could imagine how she might abandon her
ambitions of writing and dedicate her life in return for these moments
of elated, generalized love"(McEwan 287).
I do not view Briony's decision to become a nurse as an attempt to replicate or get close to Cecilia, but rather as an attempt to replace the kind of intense, territorial love she once possessed (towards Cecilia, thus causing her accusation) with a "generalized love," which leaves little room for personal deceptions and betrayels. Though she cannot eradicate her wild imagination or love for praise completely (as is proven by her decision to submit the vase story to a magazine), she realizes the devastating effects of these character traits and fights with as much pugnacity as she can muster to control her impulses. Briony, the same Briony that once jumped at the chance to be in the limelight, tries as hard as possible to dissolve herself into the sea of humanity, while still keeping her vital passions in a secure and controlled environment. This validation is opposite to those that she held as a child, and reveals, in a greater sense, Briony's ability to adapt to changes in her life and her constant effort to perfect - or at least control - herself.