Heidi Barrie (aka Hi-Ho and Didi) was a student at Sunnydale High and a bully.
On a trip school trip to Sunnydale Zoo, she and her friends take an unsuspecting student, Lance, to a quarantined area full of demon Hyenas where they try and throw him in to the enclosure. Unbeknownst to them, their actions trigger a ritual and Heidi, her friends and Xander, who had come to rescue Lance, all become possessed by demonic hyena spirits.
Forming a new pack with Xander now the leader, The Pack cause havoc at Sunnydale High, increasing their bullying behaviour, and feeling an intense desire for meat. Their now keen noses, lead them to the cage of the school’s new mascot, Herbet the pig, and he soon becomes lunch.
Temporarily separated from their leader and called into the principal’s office, Heidi and her friends haven’t quite satisfied their hunger and Principal Flutie is the next item on the menu.
Finally full they head to the woods to sleep it off while their leader is held prisoner in the school library. Having slept off their dinner, The Pack coming looking for Xander in order to reunite the pack, they rescue Xander and head off in search of more fun.
Buffy, however, has laid a trap for them and leads them back to the Hyena House where the ritual is reversed and Rhonda and her friends, a little confused, flee the scene, leaving Buffy, Giles, Xander and Willow to clean up the mess.
After her ordeal, Heidi became a vegan.