Who is Dana Joblonski from While I Was Gone and what is their importance?

Dana and Jo could pass for sisters. They have a strong physical resemblance, and upon meeting they have an instant mutual affinity. Despite coming from different backgrounds, Dana is in some ways the kind of person that Jo wants to become. She is passionate yet refuses to be tied down by conventional obligations. Dana is outgoing and free to do the things Jo has always wanted to do.