Kellin is one of the Martian colonists who crash-landed on Earth some 250 million years ago. A scientist with a general grounding in various disciplines, she's most at home as a naturalist, and is thus eager to explore and classify the strange new world they find themselves inhabiting. This puts her into conflict with some of her fellow colonists, who are more concerned with surviving and overcoming their environment than understanding it.
Kellin is fiercely protective of her younger sister, Ress-- not that Ress needs it.
The name Kellin refers to a "complete and exhaustive understanding woven within a single thread".
At the time of the crash, Kellin is 16 in Martian years-- biologically similiar to a human in their early thirties.