Sunshine has many ranges of emotions. Some say she seems mentally unstable, others think she's just odd and feels a lot more than others do.
She cries a lot, even when she's happy. They come out in blue globs that seem connected to her eyes. When she's feeling extreme happiness or saddness, there are several rings in her eyes, rather than a whole pupil.
Sunshine is constantly working to getting better and more stable in her mentality. Sometimes it's hard for her, despite her name.
She is very lonely
More art of her: http://pigeonbby.tumblr.com/tagged/sunshine