I have very specific songs that I prefer to listen to while working on my Underland inspired fics. Most of them pertain either to a specific character or the interaction between certain characters. Here's a few examples.
Tarrant: Beautiful Disaster by Kelly Clarkson
"He's magic and myth
As strong as what I believe
A tragedy with
More damage than a soul should see"
Alice:I Like It by Lacuna Coil
"Today I'm gonna fly
There's nothing that can keep me on the ground
Touch the sky, I'm free inside"
Mirana: Paper Flowers by Evanescence
"I lie inside myself for hours
And watch my purple sky fly over me
Don't say I'm out of touch
With this rampant chaos, your reality
I know well what lies beyond my sleeping refuge
The nightmare I built my own world to escape"
Hamish/Alice/Tarrant: According to You by Orianthi (I'm normally not very into this kind of song, but it's fits the trio so perfectly!)
"Everything is opposite, I don't feel like stopping it
So baby tell me what I got to lose
He's into me for everything I'm not
According to you"
Tarrant after Alice leaves Underland: 1000 Words by Sweetbox from Final Fantasy X-2
"Wait for me, I’ll write you letters
I could see how you stammered with your eyes to the floor
But still I swore to hide the doubt when I turn back the pages
Anger might have been the answer
What if I'd hung my head and said that I couldn't wait?
But now I'm strong enough to know it's not too late"
Underland: Key of the Twilight by Yuki Kajiura from the .hack//sign anime series
"I believe in fantasies invisible to me
In the land of misery I'm searching for the sign
To the door of mystery and dignity
I'm wandering down, and searching down the secret sun"
So what kind of music do you think represents different characters or parts of the world?