In The Return, Stefan arrived at Elena's house and examined Jeremy, confirming that he wasn't a vampire. Stefan then watched Jeremy while Elena goes to the hospital to check on Caroline. When Stefan comes downstairs, he sees "Elena", who is really Katherine. Stefan quickly realizes who it is and immediately throws her over the couch. Katherine breaks his arm, and then leaves when Damon and Elena walk into the house. Stefan asks Damon how Katherine had fooled him and Damon replied that he had kissed her, thinking he had kissed Elena. This upsets Stefan and he was about to attack his brother, but Elena stopped him.Katherine stabs Stefan.
Stefan and Elena went to question John about the attack, but John insulted Elena's love for Stefan and offended her. Stefan then threatened John's life by giving him blood to turn him into a vampire, and would do it if John didn't leave town. Stefan arrived at the Lockwood Estate in time to stop Katherine from attacking Bonnie. Stefan tried to get Katherine to spill why she was there, ignoring her flirting. Katherine told him she had comElena Taking care of Stefan's wounds
e back for him, but when he responded that he hated her, she stabbed him and said that it was the beginning of a love story—not the end.Stefan consoles Elena.
Elena took care of Stefan's wounds until Damon came and she went to see how Jeremy and Jenna were. Damon was ready for a fight, but Stefan refused, knowing this was what could tear them apart with Katherine on the loose. Katherine got under Damon's skin and Damon killed Jeremy with the intention of turning him into a vampire, but due to Jeremy's ring, Stefan was able to identify that he was still human.Stefan and Elena defend Caroline against Damon.
In Brave New World, at a carnival, Damon challenged Stefan to hand-wrestleMason Lockwood but Stefan lost. Damon thought he hadn't been trying, but Stefan admitted that he actually had and Mason was unnaturally strong. Damon decided to compel Carter, a worker, to get in a fight with Tyler Lockwood and see how Mason reacted. Stefan spied the fight from a far and witnessed Mason's unusual fighting against Carter. When they left, Carter was confused by why he did what he had done, and Stefan told him he was at the wrong place at the wrong time.
Stefan comforts Caroline.Stefan tried to give Elena a normal day, but the revelation of Caroline's transformation into a vampire was a shock. Stefan was furious that Katherine would do this to her, and was in agreement with Damon that Caroline should die (because of what happened to Vicki Donovan). While talking to Elena, Stefan was distracted when he smelled blood from Caroline's victim. He and Elena arrived just in time to stop Damon from killing Stefan mentors Caroline. Caroline.
Stefan took her off to the bathroom to clean the blood of her face. Caroline was disgusted and horrified by what she had done and freaked out when she saw her eyes change to black. Stefan got her to calm down and showed that this was completely natural. Caroline asked him why Katherine had done this to her, but Stefan didn't know. Afterwards, Stefan convinces Bonnie to create a lapis ring for Caroline and begins to teach her how to live on the animal diet. At the realization that Mason Lockwood was a werewolf, he even tried to protect her.
In Kill or Be Killed, Stefan tried to make peace with Mason who told his secret to Elizabeth Forbes, the sheriff, who went about trying to destroy the brothers. This time Caroline came to the brothers rescue. Knowing that he was too weak from his diet, Stefan decided to start taking small amounts of human blood every day, and Elena who was against it at first, started to help him by giving him her own blood.The brothers are taken by the sheriff and her deputies.
In Plan B, Stefan jumps into a well to try and find the moonstone that Mason hid, but didn't realize the water was full of vervain and he couldn't move, his face and body beginning to burn; Elena comes down to rescue him. After a dangerous situation in which Jenna, Elena's aunt, stabs herself after being compelled by Katherine, Stefan and Elena realize that it was a mistake not listening to Katherine and allowing themselves to challenge her, and decide to break up, despite their affection and deep love for each other.
In Masquerade, Stefan and Damon decided to kill Katherine at the Masquerade party, Alaric, Bonnie, Caroline and Jeremy helped them. At the party when Katherine came he had to dance with her or she would kill someone. Katherine told Stefan that she wants the moonstone back and when he told her that she can't have it Katherine killed Amber Bradley and left her in Stefan's arms he put Amber body in his car. Stefan returns to the party and says to Damon they need to call the whole thing off, but Damon convinces him to change his mind. Later Stefan and Damon is in the room were Bonnie had cast a trapping spell.Stefan fighting Katherine with Damon.
Caroline lured Katherine inside the room, then the brothers attacked Katherine. Stefan and Damon continue fighting, and when Damon is just about to drive the stake through Katherine's heart Jeremy comes and says "Everything you're doing to her is hurting Elena" both Stefan and Damon stop. Trapped inside the room Stefan realizes something. He remembers that Katherine told him that she gave George Lockwood something that he needed to make him help her fake her death, he figures it's the moonstone. He asks Katherine why she needs it back but Katherine doesn't answer him.
Lucy appears, getting their attention, she gives the moonstone to Katherine. All of a sudden Katherine starts gasping and falls. Lucy says that Elena is fine and that the spell is broken. She apologies for her involvement to the Salvatore's and leaves. Stefan the goes out to Elena while Damon traps Katherine in the tomb. Stefan tries to get back with Elena, but she refuses and decides to wait until she makes sure that she and her loved ones are safe first.
In Rose, Stefan and Damon have to rescue Elena, when she is kidnapped and held by two vampires called Trevor and Rose. When Stefan finds Elena, he and Damon work together to bring down another vampire called Elijah. In the tenth episode he goes into the cave to save Jeremy from Katherine. He got stuck in the tomb with Katherine because Bonnie is unable to release the spell over it. However, Elijah made a deal with Elena; to get Stefan out of the tomb, and so he kept the deal and got Stefan out and compelled Katherine to stay in the tomb until he told her to come out. He has now started drinking vervain to build up tolerance to it.
In Crying Wolf, Stefan brought Elena to a lake house where Elena and her adoptive family used to go. When they arrived, Elena took a few moments and went into the house, leaving Stefan outside. She tricked Stefan into believing that the house was left to John Gilbert after her parents died, but she revealed the truth shortly after. Elena then invited Stefan into the house. Later that night, Tyler and Brady wanted to retrieve the Petrova Doppelgänger, Elena.
Brady shot Stefan in the chest, probably not hitting his heart and left Tyler with a gun and a stake to watch over him while Brady took Elena. Elena was smart enough to hide around the house while Brady searched for her. Brady was stabbed a couple of times by Elena. Elena rushed towards the door and out and when Brady came out in pursuit, Stefan pulled his heart out, literally. Stefan explained to Tyler that Elena had to be sacrificed to break the curse and Tyler released him.
Stefan and DamonIn The Dinner Party, Stefan tells Elena about a dark time in his history. He states that he was a monster and fed off human blood and was worse than Damon back then. He also tells Elena the person that changed his life around was Lexi. When Elijah shows up at the lake house, Elena tricks him by stabbing herself with the dagger and subsequently stabs him with the dagger. Stefan then gives her his blood to heal her.
Stefan and Elena both realize that Katherine is no longer in the tomb and she's posing as Elena. Stefan then goes to Bonnie hoping that they can get the Martins on their side. Later Stefan goes to the Martin's house when Luka was just killed. Stefan tries to comfort him, but Jonas casts a spell that causes him to scream in pain. Jonas yells that he has no-one left and Stefan is about to find out what that feels like. Stefan then goes to the Grill and finds Caroline, updates her on the situation, and while she goes after Jonas, he will get Elena away. At the Gilbert house, Katherine pretends to be Elena and bites Jonas, but he soon wakes up and attacks Bonnie. Stefan then snaps his neck.Stefan finds John Gilbert dead.
When Isobel returned to Mystic Falls, Stefan and Elena wanted answers from her. He is later seen with Elena, protecting her, as John falls down the stairs, dead. Katherine kidnapped Elena and posed as her, but Stefan knew where Elena was, and he gets stabbed with vervain. He then teams up with Damon to find Isobel and Elena. After that, they give Elena their house to protect her from vampires. Damon and Stefan realized that they have a new secret weapon: Bonnie.
In The Last Dance, Stefan attends the '60s Decade Dance with Elena after Klaus starts to send his disturbing messages. He can see that something is troubling Jeremy and after talking with him, he finds out that Bonnie might die if she uses too much power to kill Klaus. He goes to Damon asking if he knew that already, and Damon admits he did. Later both Stefan and Damon help Jeremy who is being attack by students, Stefan then realizes that it was a distraction.Elena and Stefan at the 60's dance
He meets up with Elena, both rushing to find Bonnie and Damon. After Elena has freed Elijah from the dagger, Stefan respects her wishes and lets her try to talk with him alone and soon after is seen protecting Jenna from Klaus who is still in Alaric body. Later Stefan tells Damon to stop treating Andie Star like that. The brothers start to fight about Damon loving Elena, after Stefan says that Damon doesn't have Elena's respect. They are interrupted by Elijah and Elena.Stefan sees Damon's werewolf bite.
[In the episode The Last Day, Stefan respects Elena's decision on using the Elixir that Elijah has to save her. However, when Damon fed Elena his blood, Stefan fought him and ended up with a stake in the stomach. Stefan then took Elena on a hike to watch the sunset and to have one last romantic day together. During the sacrifice he tries to exchange himself for Elena's auntJenna as the vampire but Klaus refuses saying he has plans for him. Stefan watches in horror as Elijah, instead of killing Klaus as planned, fled with him.
Klaus's plans are revealed in As I Lay Dying. Klaus offers him a deal to save Damon from a werewolf bite: he will become his right-hand man, leaving everything including Elena and Klaus will cure Damon. Stefan accepts and drinks the number of blood bags Klaus gives him. Klaus then gives his blood, the cure, to Katherine to be delivered to Damon. At first Stefan is shocked, but relieved when Elena sends him a text saying Damon is okay. As Stefan watches Klaus place Elijah's body with the rest of his family. Klaus then calls out a teenage girl from behind the crate and forces Stefan to kill her and drink her blood as his initiation. Stefan does so, and Klaus is pleased.