Lyra and Will are from Philip Pullman's trilogy His Dark Materials.
Lyra is described as a twelve year old girl, though short and thing for her age. She is very clever and quick-witted, though she received little formal education, largely let to entertain herself with the Scholars, Professors and servants of Jordan College as her caring, though exasperated and somewhat negligent extended family. In Lyra's world people have animal-shaped companions who are embodiments of their soul, and which are capable of shape-shifting until the individual comes of age; Lyra's dæmon is named Pantalaimon. He can change shape as suits, but he is more often a moth, an ermine, a wildcat, or a mouse.
Will is described as having dark features, a muscular build for his age, and a ferocity in his eyes which causes people to look away. He lives alone with his mother, whom he must take care of because of some ailment which is never made clear, but seems to be a dementia or like mental illness. He is very pragmatic, and demonstrates that he will do what must be done no matter how unappealing, as well as being very loyal and compassionate (both with his mother, and then Lyra), though he can also be stand-off-ish at first, not trusting people easily. In Will's world people do not have dæmons, but at some point in the story his soul becomes visible, and another character refers to his dæmon as Kirjava, who settled into the shape of a large cat.