Depression has been likened to both a black cloud and a black dog. For someone like Kelsea, the black cloud is the right metaphor. She is surrounded by it, immersed within it, and there is no obvious way out. What she needs to do is try to contain it, get it into the form of the black dog. It will still follow her around wherever she goes; it will always be there. But at least it will be separate, and will follow her lead.
David Levithan, Every Day
depression