Feeling Sorry for Celia

Dear Ms. Clarry,
It has come to our attention that you are incredibly bad at being a teenager
I mean, take a look at your bedroom.
You haven't got any posters on your wall. (Don't try to tell us that picture counts. A kitten drowning in a strawberry milkshake? Designed by your mother as an ad for carpet cleaner? Give us a break.)
You have a chain of old Christmas cards hanging from your curtain rod. The only makeup you have is banana-flavored lip gloss and it's melting all over your Little Mermaid quilt cover. (Actually, we don't think that lip gloss counts as makeup at all.)
Not to hurt your feelings or anything, but you're an embarrassment to teenagerhood. Therefore, could you please climb into the refigerator and wait very quietly until your teenage years end?
Thank you.
Yours sincerely,
The Association of Teenagers

P.S. You also don't seem to understand how to get a snow tan. You look like a slice of watermelon.

—Elizabeth's first letter

The protagonist Elizabeth Clarry has just learned that her new English teacher is beginning a pen-pal program between her class and a neighboring high school to rekindle the "Joy of the Envelope". Her mother, an advertising exec who takes her job very seriously, is so busy with her job that she only has time to talk to Elizabeth via sticky notes left around their kitchen, and takes every opportunity she can to pick Elizabeth's brain for ideas for new advertising campaigns. And now, her (literally) distant father is moving back to Sydney after several years of living in Canada. That'd be fine, except he wants to "bond" with her by taking her out to expensive restaurants (to "culturally educate" her) and generally be embarassing.

And then there is the eponymous Celia, who has been Elizabeth's best friend since childhood. Elizabeth is the practical, independant type. She's does long-distance running, takes care of her dog, Locche, and makes the meals for herself and her absent mother. Celia is the Cloudcuckoolander, the enchanting fairy-like one who's always trying new things out of boredom. Partway through the book, we learn that Celia has run away and joined the circus. Elizabeth is left alone, worrying if Celia will ever come back, as well as a host of other problems.

The book, instead of being witten in narrative form, is written as a series is a series of letters, notes, and postcards. Many of these come from imaginary organizations like The Cold Hard Truth Society, The Association of Teenagers, and The Society of People Who Are Definitely Going to Fail High School (and Most Probably Life as Well!).

Christina, the girl that was picked to be Elizabeth's pen-pal, is spunky, no nonsense, and a sympathetic ear to Elizabeth's problems. Although they are both wary of each other at first, especially since Elizabeth goes to a private school and Christina likes oatmeal, they soon become friends. They share stories of their families and musings on life. With Christina's support, Elizabeth begins to accept the changes that are happening in her friendship with Celia. Which is pretty spectacular considering that these are two people who haven't spoken face-to-face for roughly 95% of the book.

Tropes used in Feeling Sorry for Celia include:

Adults Are Useless: That's assuming they know something is happeneing at all. Every time a friend is in potential danger, it's up to the brigade of awkward teens to save the day.
A Friend in Need: Comes up multiple times over the course of the story, with the main thing being to rescue Celia from the circus.
Allergic to Routine: Celia's main motives for running away or doing things like disassembling Elizabeth's washing machine.
Berserk Button: Don't call Christina "Tina", or she'll break your face.
Bitch in Sheep's Clothing: Celia, to an extent. She never seems to grasp her actions hurt other people, which is especially painful for Elizabeth when Celia starts dating Saxon, whom Elizabeth had a huge crush on, after Elizabeth rescued Celia from the circus.
Brilliant but Lazy: Elizabeth, on occassion, when she is too distracted/tired/etc to train.
Brutal Honesty: The Cold Hard Truth Association, obviously.
But We Used a Condom: After Christina and her boyfriend have sex for the second time, they find out the condom broke.
Character Development: By the end of the book, Elizabeth has gained confidence in herself and no longer needs the Association of Teenagers telling her how much she sucks.
Cloudcuckoolander: Celia's entire family.
- Interestingly, Celia's mother seems to have underlying stress problems as a result of her and her children's extreme quirkiness.
Coming of Age Story
Doting Parent: Celia's mother takes this to an unhealthy extreme. Saxon's parents also qualify.
Dysfunctional Family: Everyone has one.
Floating Advice Reminder: The random notices she gets from the different clubs and societies sometimes contain advice and often contain contradictory advice, where she'll get a memo from one organization suggesting she take one course of action immediately followed by another message from a different club telling her to do something else entirely.
Granola Girl: Celia's mother .
Green Eyes: Elizabeth has them.
In Harm's Way: Celia is always running away from home to go on "adventures", though she usually at least calls Elizabeth to tell her where she's going.
Inner-City School: It is suggested that this is the kind of school Christina goes to, though whether the school is actually like this or just seems like this compared to Elizabeth's private school is argueable.
Long Lost Sibling
Looking for Love In All the Wrong Places: Christina claims her cousin Maddie runs away from home all the time like Celia, but when Maddie does it it's not out of boredom, it's for "love".
Manatee Gag: Some of Elizabeth's letters from the various imaginary organizations could be considered this. They don't really advance the plot, they're pretty much just there to be funny.
Maternally Challenged: Both Elizabeth and Celia's mothers have their own flavor of this trope, with Elizabeth's mother being the more usual super-busy sucessful career gal. She even has a sort of heart-to-heart with Elizabeth and says she feels bad for being so absent (which, of course she does by fax.) Celia's mother is too loving and supportive of Celia, not putting any limits on her because, "Celia's identity is unfurling itself slowly, like a tulip bud, and it's a breathtakingly beautiful thing to see." Which is why she never calls the police when Celia runs away.
Miss Conception: Subverted when Christina thinks she might be pregnant. Though what happened to her could very well lead to concieving a child, she remains worried about it even after having her period, thinking that it might be a "false period" and that she could be pregnant anyway.
Parent with New Paramour: Elizabeth's father, though she's not really new. Instead, the father has never bothered to introduce his new family to his old wife and kid.
Pretty White Kids With Problems: Subverted in the fact that while all the characters have problems to deal with, they're not pulled straight from the typical Teen Drama and the characters don't whine about them. Instead of Wangsting about not fitting in and no one understanding them, they instead take the odd troubles life deals them relatively in stride.
Scrapbook Story: Quite!
Strange Girl: Also Celia
The Power of Friendship
Too Good for This Sinful Earth: Celia and Saxon believe that their relationship is this way, so they make a Suicide Pact, although when interrogated about it later, Celia can't understand why everyone was so worried, exclaiming "I wasn't actually going to do it!"
Visit by Divorced Dad
Walking the Earth: One of Celia's reasons for joining a traveling circus.
Your Cheating Heart: Elizabeth's father's infidelity is actually a plot point when it turns out Elizabeth has a half-brother, Ricky Clarry, who was conceived only a few months after Elizabeth.