If you haven't read the book or seen the musical 'Wicked', it is the story of how Elphaba becomes the Wicked Witch of the West from the 'Wizard of Oz'.
I read the book before there was talk of a musical and loved Gregory Maquire's take on the iconic character. When I saw the musical, Elphaba's performance of "Defying Gravity" hit home for me pretty hard.
It seems like misunderstood beings in fiction are represented a lot with the color green... Elphaba, Kermit the frog... Slytherins. I have felt pretty 'green' at times in life myself.
'Green' people can be mistakenly perceived as 'angry', but in reality, they are just dealing with some realizations about the world involving moral dilemmas. Just like this awesome 'Star Wars' meme my husband recently shared with me found here...They probably should have made his charcter green too! Anyway, just another study, making Elphaba's portrait fell like little more like a self portrait.