Derek was born into a family of werewolves. … In order to save the life of his sister, Cora Hale, long thought dead in the fire, Derek gave up the spark that made him an Alpha. His eyes turned from red back to blue. Kate somehow physically regressed Derek back to the age of 15.

What episode does Derek turn young?

“Teen Wolf” 117 (TV Episode 2014) – Ian Nelson as Young Derek Hale – IMDb.

Why did Derek lose his powers Teen wolf?

Perhaps the act of turning into his teenage self somehow drained him of his powers. The Mexican cave where Scott found Derek somehow triggered the Benjamin Button process and while teen Derek did have his wolf powers, it seems as though since returning to his actual age, Derek is getting less and less powerful.

The aunt of Allison Argent and the sister of Chris Argent, Kate was a werewolf hunter who goes against the codes that they follow. She is believed to be killed by Peter Hale but makes a triumphant return to Beacon Hills, now a Werejaguar. She is the main antagonist of Season 4.