Spoiler warning: this article reveals the Alpha's identity and the ending of all 12 episodes of Teen Wolf season 1 (2011).
The Alpha who bites Scott McCall is Peter Hale, Derek's uncle. His identity is revealed to viewers in Wolf's Bane, episode 9, while Scott confronts him directly in the following episode. In the finale, Code Breaker (episode 12), Derek kills Peter, becomes the new Alpha and deprives Scott of the opportunity he believed might reverse his transformation.
The mystery shapes the whole season: Scott must learn to control his werewolf body, Stiles tries to identify his attacker, Derek hunts whoever killed his sister, and the Argent family turns the investigation into a hunt. The sequence below tracks those clues without retelling every subplot from all 12 episodes.
From the bite to the mistaken suspicion of Derek
In Wolf Moon (episode 1), Scott joins Stiles in a search for a body in the woods of Beacon Hills and is bitten by a creature he cannot identify. Enhanced strength, senses and reflexes soon follow, even as he tries to keep up with school, lacrosse and his relationship with Allison Argent. Things become more dangerous when he learns that her relatives hunt werewolves.
Derek Hale initially looks suspicious: he knows how werewolves work, is connected to the victim found in the woods and withholds information. But in Pack Mentality (episode 3), Scott learns that Derek did not bite him. Both are Betas, and the unknown attacker is a more powerful Alpha. The question shifts from what Scott has become to who wants to control him.
The clues leading to Peter Hale
- Episode 1, Wolf Moon: the bite takes place in the woods, and the attacker's face stays hidden. Scott suspects Derek but does not yet know the difference between an Alpha and a Beta.
- Episode 3, Pack Mentality: Derek rules himself out and explains the existence of an Alpha. The search turns toward another werewolf.
- Episodes 6 to 8: the Alpha's attacks, pressure from the hunters and Scott's struggles during the full moon show that the enemy also threatens Derek and the group. Viewers still lack a definite answer.
- Episode 9, Wolf's Bane: the investigation leads Stiles and Derek to Peter Hale, a patient badly burned in the family house fire. Peter is revealed as the Alpha; Derek realizes his own uncle is involved.
- Episodes 10 and 11, Co-Captain and Formality: Peter approaches Scott and tries to recruit him. Meanwhile, Kate reveals the Argents' traditions to Allison, and Scott's secret finally comes out.
- Episode 12, Code Breaker: the clues involving Laura Hale, the fire and the killings converge. The battle against Peter changes who holds the Alpha position.
That order matters because viewers learn the truth about Peter before Scott does. In episode 9, the reveal comes through Derek and Stiles' encounter; in episode 10, the Alpha approaches Scott and tries to justify his actions. The characters do not receive the same information at the same time.
Why Peter became an Alpha and how the fire connects
Peter survived the Hale house fire with severe burns. His niece Laura, Derek's sister, possessed Alpha power before she was killed. Peter gains that power by killing her, which also speeds up his physical recovery. In Wolf's Bane, he claims he was still unable to control his instincts when Laura died, an explanation meant to win Derek's sympathy.
The finale adds a crucial detail: Scott finds evidence that Laura was lured back to Beacon Hills by a clue connected to Peter's nurse. To Scott, this undermines the story of an accidental attack and helps persuade Derek to stand against his uncle. The fire also gives the killings a pattern: Peter targets people associated with his family's destruction. Revenge explains his stated motive, but does not justify the murders.
On the other side is Kate Argent. She is identified as responsible for the fire that killed members of the Hale family, and her actions violate the code defended by Chris Argent, which distinguishes dangerous werewolves from innocent people. The conflict is more than a feud between two families: an earlier crime drives the present attacks and shapes Allison's judgment of her aunt.
The Code Breaker showdown and how Derek gains power
In the finale, Kate uses Allison to help capture Scott and Derek. Chris intervenes when he recognizes that his sister has crossed the hunters' moral boundary. Peter arrives and kills Kate to avenge the Hale fire. Scott and Derek then try to stop him, but the Alpha takes on a monstrous form and gains the upper hand.
The outcome takes more than two werewolves. Stiles and Jackson bring incendiary devices that weaken Peter, and Allison helps with her bow. Once Peter falls, Derek delivers the fatal blow. His eyes turn red, and he declares himself the new Alpha. As shown in this season, the power changes hands when the previous Alpha is killed, not because Derek receives a new bite.
Scott wanted to kill the werewolf who bit him because he believed doing so might cure him. Derek strikes first and closes off the option Scott hoped to pursue. That does not establish that the cure would have worked: the season presents Scott's belief without showing an actual reversal of lycanthropy. The certain outcome is that Scott remains a werewolf and Derek now holds Alpha status.
What the finale resolves and leaves unanswered
Scott and Allison reconnect after she learns the truth, although the conflict with her family's hunting tradition remains. Lydia survives Peter's attack without undergoing the expected transformation, raising questions about her condition. Jackson, who has been seeking the bite, approaches Derek after the change in leadership. These are season-one cliffhangers; later-season revelations are unnecessary to understand who the Alpha was and why Derek replaced him.
