A person becomes a wendigo as a curse for resorting to cannibalism to survive in cold forested areas. A fully transformed wendigo is a fey creature that looks like a ragged and twisted version of its former self, with charred bloody stumps in place of feet. It can run high in the air at tremendous speeds, and can drive a person mad by whispering to them and being seen constantly out of the corner of their eye. Keller, who has not completed the transformation yet, is essentially a crazy person.