Derek starts his pack in Season 2 by biting Isaac, Erica, and Boyd over the course of the first three episodes. Peter joins the pack in 2x11 Battlefield, although he is not liked or trusted by anyone. Scott was briefly a part of Derek's pack from 2x07 Restraint to 2x12 Master Plan, but this was subterfuge. Stiles implicitly joined along with Scott, although he was not aware that Scott had joined under false pretenses. Even after Scott betrays and leaves Derek's pack, Stiles shows affinity for them and there are hints he may have worked with them in attempting to rescue Erica and Boyd from the Alpha Pack over the summer between seasons 2 and 3A. Erica was killed by Kali before they were able to rescue her, but Boyd was rescued along with Derek's long lost sister, Cora, in 3x02 Chaos Rising. Boyd is later killed by Kali and the twins forcing him onto Derek's own claws in 3x07 Currents, an event which shatters Derek. In 3x11 Alpha Pact, Isaac abandons Derek's pack for Scott's sortly before Derek gives up his alpha spark to heal a dying Cora who had been poisoned by Jennifer Blake.