Lullaby is a very special character to me.
Think of her like Aphrodite/Venus. She is the connection to God. She is Gravity's (God's) sister, but while he is God-like, she is more Demi-God like, and enjoys spending time on the Earth with others. Her usual goal in a lifetime is that of a guardian. She has lived many, many lifetimes. She represents love, a connection to god/spirituality, sexuality (in a beautiful way), beauty, self-sacrifice, and immortality.