Peter Hale

When Kate Argent set fire to the Hale house, Peter, who was in the house with his family at the time, was considered the only survivor of the fire (in the third season it turned out that his niece Cora was also alive). From the shock he experienced, he fell into a coma and spent 6 years in this state

The essence of the werewolf throughout all these years has allowed him to heal, albeit very slowly. When he wakes up, he tricks his niece Laura Hale, Derek's sister, into returning to the city, after which he kills her and becomes an Alpha, because this is the only way he can avenge those who died in the fire - for his family. By becoming an Alpha, Peter was able to make a huge leap in healing.Wanting to become even stronger, Peter bites Scott McCall, who is at that moment near the Hale house, which leads to the transformation of the latter into a werewolf.

Next, Peter kills the school bus driver, but Scott, who saw in a dream how he commits the murder, believes that it is his fault.

For most of the first season, Peter was in the guise of an Alpha, while attacking people. 

When Kate Argent, Chris Argent's sister, returns to the city, who, as it later turned out, set the Hale house on fire, Peter, still in the guise of an Alpha, chases her car at the entrance to the city. As a result of this attack, Derek was shot with a weapon loaded with wolfsbane bullets. While running away, Peter draws a huge spiral on the roof of the building.

Later, Peter kills a salesman in a video store, which gives him the opportunity to kill Jackson Whittemore, however, after seeing the marks left by Derek on the guy's neck, he changed his mind. Lydia Martin captured him leaving the scene of the murder in the form of an Alpha on her smartphone, as well as a surveillance camera located nearby.Soon after, Peter waylaid Scott near the Argent house and drew a spiral on the fogged glass of his car. Later, Derek will explain that the spiral is a sign of retribution.

At Scott's call, Peter arrives at the school, where he attacks Derek and seriously injures him, after which he pursues Scott and Stiles, killing the janitor in the process. After that, he sends Allison Argent a message on behalf of McCall asking for help, thereby luring Allison, Jackson and Lydia into a trap.

Trying to save the others, Scott goes to the gym to fight the Alpha, but he has some effect on McCall and he, transformed into a werewolf, tries to kill his friends.

He also tries to kill Adrian Harris, a chemistry teacher who was supposed to give some information to Laura Hale, which is why she returned to the city, and then, in the hospital, tries to kill Stiles, but Derek prevents him. After fighting, they come to a common opinion: it is necessary to take revenge on the hunters for the murder of the family.

Peter and Derek try to convince Scott to join them. Peter, digging his claws into Scott's neck, passes on his memories of the fire, but Scott refuses Peter's offer. Hale then invites Scott's mother, Melissa McCall, on a date and says he will bite her if Scott doesn't join the pack.

Next, Peter goes to Dr. Deaton to pick up McCall, but he was stopped by a barrier in the form of a rowan balustrade. In desperation, he throws a chair towards the vet, but it has no effect, so Peter goes in search of Scott's friends and soon finds Allison in a clothing store. Soon, during a school dance, on the lacrosse field, Peter attacks Lydia and bites her, and Stiles, who appeared in time, is threatened with violence if he does not help him find Derek, who in turn was taken by hunters.

During the search for his nephew, Peter offers Stiles to become like Scott – a werewolf, but Stilinski refuses.

What follows is a battle in which Peter easily defeats the hunters and Scott, wanting only Kate Argent, who started a fire that destroyed his entire family. He takes her into the house, demands an apology, threatening to kill her niece. But after hearing them, he still tears Kate's throat in front of Allison, because he considered the apology insincere.Stiles and Jackson arrive in time and throw Molotov cocktails at Peter, who has already left the mansion in the form of an Alpha, and Hale burns alive. After receiving serious injuries, he turns back into a human, and then Derek takes revenge for his murdered sister and rips his uncle's throat, becoming an Alpha at the same time.