Eustace Swiftrunner is a totem fox encountered by Michelle Jocasta in the Springfield Avalon. He is the owner of the Avalon, and seems to be fond of collecting various mythical pets, such as a byzantine eagle and a vegetable lamb. When Michelle first encountered Eustace, he resembled a humanoid fox with long, braided hair and wearing a pair of overalls.
From the Skin Deep Character Page: "Eustace is the owner of the Southwest Missouri Avalon frequented by Michelle and her friends. Avalons are mythical safe-houses away from the prying eyes of humans. Very proud of his Osage tribe heritage, Eustace has an extensive knowledge of local folktales, legends, and traditions."
"Marshall is Eustace's best friend....Eustace lives vicariously through Marshall, preferring to hear of Marshall's adventures rather than going on any of his own."
Eustace first appeared in Orientations Part IV, page 17, when Jim Finn suggested that Eustace might be a helpful source of information about the Missouri Monster. Eustace had heard of the MoMo, but had never seen it, and was very excited to learn that it did, in fact, exist.
In Orientations Part V, he tried to help Michelle escape The Bloodcarver by sneaking into Fiddler's Cave and releasing her from the ropes that bound her arms. After Bloodcarver released Michelle, he followed him back to the cave and witnessed the exchange that went on between The Bloodcarver, Grim Brothers, and Gabe.
Totem animals are considered to be very magical creatures and seem to be able to take on many different forms without the help of medallions. Eustace has appeared in the form of a humanoid fox (see picture above), and as a normal fox with glowing eyes. He wears a couple of Marshall's feathers for good luck. He was also able to sense what sort of creature Michelle was just by looking at her , and while he figured out that she was a flying feline from the Mediterranean, he guessed incorrectly at exactly what species she was. According to the Reader Questions, Eustace has a fondness for Bluegrass music and plays the mandolin.