“Don't you realize what you're dealing with? I'm an Alpha.” — Ennis to Scott
“Ready for a rematch?” — Ennis to Derek
Ennis was once the Alpha of his own pack. When one of his pack is killed by the hunters, he becomes angry and vengeful. Deucalion advises Ennis not to take his revenge on the hunters, having a vision of peace between werewolves and their hunters. When Ennis goes to look at the body he is told he is not allowed to and no matter how close they were, they were not family, but Ennis begs to differ.
Shortly later, Peter Hale, whose nephew Derek was in love with a human named Paige, comes up with an idea to help out Derek's relationship, and Ennis's loss—by having Ennis bite Paige. Soon, Paige is asked to meet Derek at the school but Ennis attacks her instead, and when Derek comes, he tries to stop Ennis, but she is already mortally wounded and is forced to perform a mercy kill.
In the present day, Ennis dresses as a hospital orderly to abduct a teenage werewolf named Issac. Issac's friend Scott comes to his rescue and fights Ennis before Derek arrives and manages to fight Ennis off. Ennis later meets Derek at his home, along with the rest of the Alpha's. There Deucalion tries to convince Derek to kill one of his own pack.
When Scott, his friends, and Derek's pack arrives at an abandoned mall to meet the Alpha pack, a fight ensues. With Ennis and Kali's combined efforts, they get the upper hand before Allison Argent arrives and fires flash-bang arrows. Derek and Ennis fight each other and near a ledge with a three floor drop. Scott tries to help by slashing Ennis's legs, causing Ennis and Derek to fall off the ledge.
Ennis survives but is taken to Dr. Deaton's office, where he remains unconscious. The Alpha pack come to collect him, and Deaton says he will heal, but Deucalion simply crushes Ennis's skull, killing him.