It's no secret that transformation is at the heart of this myth. First, Zeus transforms into Artemis to seduce the nymph. Then, he transforms Callisto from a not-pregnant nymph into a pregnant one (using the traditional process). As a punishment, Artemis transforms her loyal follower into a she-bear. And to top it all off, Zeus then transforms Callisto and their son, Arcas, into the constellations Ursa Major and Minor. Dude, how many transformations can one myth take?
Callisto faces one type of exile after another in this story. First, she's exiled by her beloved goddess, Artemis, when Artemis finds out she's pregnant. Artemis's brand of exile is particularly harsh because it also separates Callisto from her own species by forcing her to live out the rest of her days as a she-bear in the wilderness. Then, in the end, Zeus saves Callisto from being killed by her hunter son, Arcas, by placing them both in the sky as constellations. While this is meant as a reward of sorts, it's also another kind of exile. Callisto may have a great view of earth, but she'll never set foot (or paw) on it again.