In the first season of the show it is stated from the very first episode, by Stefan himself that he and Caroline would never be together. After that they don't have any other meaningful scenes together. Stefan is mostly hung up on Elena for the first season.
After Caroline is turned into a vampire her personality changes completely. Stefan, helps her deal with her new state and in this way they come a lottle closer together as friends.
The third season is pretty uneventful for Steroline as they continue to develop their friendship, but that is as far as they go.
In the fourth season Stefan and Caroline have developed a very strong and special bond, which only grows stronger when Stefan breaks up with his girlfriend Elena. Stefan declares Caroline his sober sponsor, which she takes very seriously.Caroline lets Stefan crush at her place for a while after Elena has moved in his house, because her brother wants to kill her. After that Stefan and Caroline figure out that Elena is sired to Damon together. When Elena shuts off her humanity, Stefan and Caroline are constantly together, making sure she doesn't kill anyone. They dance together once at a party, thrown by Elena, and they also dance at the decade dance, where Caroline tells Stefan that "One day you'll meet someone new, and you'll have moved on without even realiseing it."
In season five it is stated by both Stefan and Caroline that they are best friends. When Stefan finds out about Caroline and Klaus Mikaelson, he seems hurt but he is there for her when Tyler gets mad at her, and he convinces her that she is a good person even when she thinks she is not. Stefan and Caroline figure out that Elena has been possessed by Katherine together and they try to find a solution to that problem. When Damon dies at the end of the season, Caroline hugs and comforts Stefan, though she lost her best friend as well.
After Damon's death Stefan leaves town without telling anyone which hurts Carooline, who keeps sending him voice mails, filling him in with what is going on with their lives, and practically begs him to come back, telling him that they need to be together, at this difficult time. In the meantime Stefan has decided to move on from Mystic Falls completely, so he never answers his friends' calls or listen to Caroline's messages. When Caroline and Enzo visit Stefan at his new house, they leave Stefan speechless. They also discover that Stefan has a new girlfriend, who Enzo kills at the end of the episode. Caroline decides to face Stefan and she states that she was completely falling apart without him which hurts Stefan but he doesn't give in. After that they get into a huge fight. When Stefan comes back Caroline thinks that he would apologise but Stefan claims that he only came back to get his revenge on Enzo. After a few episodes they go on a mission together and when Enzo realises that Caroline has fellings for Stefan, he tells him, which makes things even more awkward between Stefan and Caroline. After that Stefan tries to make things right with Caroline by helping her with Christmas preparations, but Caroline keeps pushing him away, until her mom faints and they have to take her to the hospital. There, Caroline tells Stefan she hates him after his asking of why she had a thing for him. In the next episode it is inferred that Caroline left Stefan out of friendsgiving. Later on when Stefan finds out that Liz has cancer, he decides that he should tell Caroline. When he tells her she hugs him and he comforts her and it is like all the anger goes away. After that Stefan helps Caroline deal with the fact that her mother will soon die and they share their first kiss while preparing their lake house for Liz to go live befor she dies. Unfortunately, Caroline's mum died before Caroline got to say goodbye and she is mad at herself for kissing Stefan and not being with her mom at her final moments. After the funeral Caroline shuts her humanity off and after a short while, she forces Stefan to do the same. Stefan wants to make Caroline's life miserable so he won't be the only one drowning in mistakes after he turns his humanity off. But that ends up with them having sex and being a murder couple. When Stefan sees his mother, when she was supposed to be dead his humanity comes back, but he acts like it hasn't in front of Caroline because as it turned out, he was her emotional trigger. Finally he manages to turn her humanity back on, but then she walks out on him, because she feels too guilty. At Rick's wedding, she tells him that she can't be with him. After that dreadful wedding when they visit Elena at the hospital, Caroline questions his feelings towards Elena, but he assures her that they are only friendly. In the last episode of the season, Stefan appears at Caroline's doorstep at tells her that he will wait for her, which is followed by a short kiss on the cheek.
After Stefan's confession, things are a little awkward for Stefan and Caroline, and they decide to be just friends, but that changes when Caroline kisses him. After that Caroline is kidnapped by the heretics Stefan was very worried. When she finally came back, she had a spell on her which prevented vampires from touching her, and she was also extremely jealous of Stefan's ex-girlfriend Valerie. They convinced a heretic to absorb the spell from Caroline and then they had sex. As we discovered three years later Caroline was engaged with Rick and had two daughters with him, which are not Caroline's, they were just tranferred into her by the gemini coven. When Stefan finds out about it he avoids the subject but he later tells her he loves her no matter what and she says it back. When Stefan is marked by the huntress he leaves town and goes off to New Orleans where he admitts that he loves Caroline to Klaus Mikaelson. Three years later when they meet again Caroline is furious at him for leaving her, but when she is found with the same choice as him she kind of forgives him. They finally get back together in the last episode.