The Vampire Diaries (season 4)

The Vampire Diaries, a one-hour American supernatural drama, was renewed for a fourth season by the U.S. channel The CW on May 3, 2012, seven days before the third season's finale. Unlike the previous seasons that aired in September, it premiered on October 11, 2012, to avoid competition from major television shows. Season 4 consisted of 23 episodes instead of the usual 22 episodes. All the previous season's characters returned as series regulars apart from Matthew Davis, who was killed off in the Season 3 finale but made guest appearances in the second, twenty-second and twenty-third episodes of the new season.
On January 11, 2013, it was announced that a back-door pilot focused on the Originals, titled The Originals will air on April 25 for series pick-up^. On April 26, 2013, The CW announced that The Originals, The Vampire Diaries' spin-off series, was picked up for a full season slated to premiere next fall.
On February 11, 2013, The CW renewed the series for a fifth season.

season 3

Season three opens the door to learn more about Klaus and The Original Family as his motives for wanting Stefan on his side are finally revealed. As Stefan sinks deeper into the dark side, Damonand Elena struggle with the guilt of their growing bond even as they work together to bring Stefan back home. The ghosts fromJeremy’s past have a powerful message they’re trying to deliver to him, not to mention the impact they’re having on his relationship with Bonnie Bennett; as Caroline and Tyler grow closer, a war erupts between their families.

The series stars Nina Dobrev as Elena Gilbert, Paul Wesley asStefan Salvatore, Ian Somerhalder as Damon Salvatore, Steven R. McQueen as Jeremy Gilbert, Kat Graham as Bonnie Bennett,Candice Accola as Caroline Forbes, Zach Roerig as Matt Donovan, Michael Trevino as Tyler Lockwood, Matt Davis as Alaric Saltzman and Joseph Morgan as Klaus.

Based on the series of books by L. J. Smith, THE VAMPIRE DIARIES is from Alloy Entertainment and Bonanza Productions Inc in association with Warner Bros. Television and CBS Television Studios with executive producers Kevin Williamson ("Scream," "Dawson's Creek"), Julie Plec ("Kyle XY," "Wasteland"), Leslie Morgenstein ("Gossip Girl," "Private") and Bob Levy ("Gossip Girl," "Privileged").

in season 3 Stefan has to team up with the evil klas in order to save his brother Damon after he was bitten by a werewolf and nearly on the verge of death. so Stefan had to go to klas and trade his service to klas for klas's blood.