What themes are there throughout the series??

I have to do an English assignment. and I have to find "themes" in these books, throughout the series. Any ideas?

Ahh, English how I lothe thee. (I'm stuck in AP Language and Compisition, ach!)

The obvious one:Friendship: How Gemma, Ann, Fee, and Pip's relationship grows and changes throughout the series.

The coming of age: The girls approach adulthood in a world where their future is decided for them, but they mature themselves how they want. (ex. Gemma=University in America, Fee=Model in Paris, Ann=Actress, Pippa=the afterlife)

Love: Gemma/Simon, Gemma/Kartik, Fee/Pip, Fee/Ithal. No matter how bad or good the relationship was, it happened.

Death: It plays a major role here (Mary Dowd aka Virgina Doyle, Kartik, Pippa, Ms. McCleethy, Eugena Spence,...?(gah, I haven't touched these books in a long time) If these people didn't die, the whole series would be different.

Hope I helped