|“|| Stefan: Why do you care what happens to Elena, huh? In a minute, you're gonna be dead anyway.
Bonnie: And you're gonna be human!
Their relationship is mostly a friendly one, even though it went through some tension after Sheila Bennett's death and especially after Stefan murdered Enzo St. John in front of Bonnie. Although they do not interact much throughout the series, they can still count on each other as allies. Whenever things go south for them or their friends, they always seem to be on the same side.
The friendship between them is referred to as "Stefonnie" by fans.
Throughout The Vampire Diaries Series
In The Night of the Comet, she gives Stefan Elena's number but sees a vision as well that makes her pull away from him.
In Friday Night Bites, Bonnie became worried of Elena's strong involvement with Stefan and she even refused to go to the dinner that Elena planned so Bonnie can get to know Stefan.
When Bonnie became possessed by Emily Bennett's spirit and destroyed Damon's plan to free the tomb vampires, he bites Bonnie and almost kills her, however Stefan quickly gives her some of his blood to heal her. That night Elena tells Bonnie what Stefan really is.
In Bloodlines, Stefan needs Bonnie's help in order to find Elena and Damon. But becomes worried when her powers aren't working. Later Stefan opens up to Sheila in his effort to help Bonnie overcome her fears and accept her powers again.
In Miss Mystic Falls, Bonnie returns to Mystic Falls, she is not too happy to see Stefan or Damon and blames them for Sheila's death. When Stefan loses control and feeds on someone, Bonnie uses her powers to stop him.
In Isobel, Stefan goes to Bonnie for help after Isobel's dangerous actions.
In Founder's Day, Bonnie helps Stefan save Damon from a burning building. But later, she tells Stefan that the next time Damon misbehaves, she will kill him.
In The Sacrifice, Bonnie once again comes to Stefan's, as well as Damon's aid. She tries to break the seal on the tomb, but Stefan tries to stop Bonnie because she is not strong enough for it.
In Know Thy Enemy, After Bonnie gets an upgrade on her powers, Stefan realizes that Bonnie is their new secret weapon against Klaus.
In The Last Dance, Stefan is worried for Bonnie's safety after finding out from Jeremy that if she harnesses too much power she could die. Later he learns from Damon where Bonnie is.
In As I Lay Dying, Stefan goes to Bonnie for help in finding a cure for his brother, who had been bitten by a werewolf.
In The New Deal, Stefan steals Klaus's coffins in which his family are in, and hides them. He calls Bonnie for help and tells her about his plan, Later, Bonnie and Stefan go to one coffin, of which Bonnie dreamed about, and they notice that it won't open. Bonnie discovers that the coffin is closed with a powerful spell.
In Our Town, Bonnie is still working with Stefan on discovering how to open the coffins.
In The Ties That Bind, Stefan is angry at Bonnie for telling Elena about his plan and and about the coffins. Bonnie tells Stefan they need Elena's help. She shows him a picture. Stefan asks who it is in the picture and Bonnie states that it is her mother, Abby Bennett Wilson, and she can help them open the coffins.
In Promised Land, Stefan is killed and has to pass through Bonnie to get to the other side. He wants Bonnie to reassure him that she found a way to bring him and everyone else back, but she lost it and said that she was sorry.
In Home, As Bonnie is bringing people back from the other side, she spots Stefan and Lexi and tells them that they don't have much time. Stefan wants to wait until he finds his brother, but Bonnie falls and Stefan touches her, bringing him back.
In I Would for You, Bonnie assists Damon in helping contain Rayna Cruz being her life is linked to Stefan. Damon saves Rayna's life being he bears the hunters mark for Rayna to kill him, but this also links their lives if Rayna does die.
In Somebody That I Used to Know, Damon calls Stefan while Stefan is trying to get into contact with Caroline Forbes and asks Stefan to assist Damon in killing Rayna Cruz's marked-vampires from her destroyed-Phoenix Sword. Stefan hesitantly accepts because Bonnie's life is on the line and both Damon and Stefan care about whether or not Bonnie dies.
In Requiem for a Dream, Stefan helps Damon, Caroline and Enzo to try and get through to Bonnie. Stefan shares a tense reunion with Caroline as he tries to assist Caroline in talking sense while Caroline is inside Bonnie's head. This proves to be unsuccessful being Bonnie's Supernatural Huntress was strong enough to invade her sane mind.
In Gods and Monsters, Stefan, Caroline and Alaric team up using Alaric and Caroline's daughters in opening the doors to the Armory. Stefan does this in order for Damon to burn the last body linked to Bonnie's ties with being a Supernatural Huntress. This proves to be successful in the end, which reunites them with their lovers, Caroline and Enzo.
In Hello, Brother, Stefan and Bonnie continue to search for Damon and Enzo. Months have passed and Bonnie has lost hope as she remembers her happy times with Enzo, the love of her life. Stefan convinces Bonnie to come along to help him find Damon and Enzo one day when they get another tip on their whereabouts. However, when Stefan and Bonnie find them, Damon violently puts Bonnie in a chokehold and threatens them to leave and not come after them again. This sparks hope inside both Stefan and Bonnie, especially when Bonnie believes that Enzo is trying to help defeat the Armory's monster.
In Today Will Be Different, Stefan and Bonnie continue to work together to try and save Damon and Enzo from Sybil. However, specific circumstances force the both of them to separate and work on saving them on their own. Bonnie gets a tip and eventually finds Enzo, but she fails to bring him back due to Sybil's mind control over Enzo. Stefan also finds Damon, but Damon kills Sarah Nelson, ordered by Sybil. This leaves Stefan devastated that he lost both Sarah and Damon to the monster. Both Bonnie and Stefan are extremely disappointed that they couldn't save Enzo nor Damon.
In You Decided That I Was Worth Saving, when Sybil orders Enzo and Damon to fight to the death until Bonnie makes the decision to save either one of them, both Bonnie and Stefan are forced to defend either Enzo or Damon. Stefan decides to side with Damon and Bonnie eventually chooses to save Enzo over Damon when Sybil forces her to do so. However, after Stefan and Bonnie and the rest of their friends are able to subdue Sybil and Enzo, Stefan and Bonnie are next seen together inside the Armory staring at Sybil in a prison room.
While staring at Sybil lying on the prison room's bed, Stefan and Bonnie begin to converse casually about the day's events. Bonnie asks Stefan if he had to, would he save Damon and leave Enzo for dead. Not bother to lie to her, Stefan says that he would have chosen to save Damon without hesitation. Then Bonnie gives Stefan a look and explains that Enzo has been the one fighting Sybil's control. She also tells him that Enzo's fighting would have been for nothing if Stefan let him die and saved Damon. Bonnie continued to argue that Damon wasn't the one fight and explained that Enzo was at least fighting for his life. Stefan sighs as Bonnie angrily leaves him with that thought.
In You Made a Choice to Be Good, Stefan had already figured out that Bonnie removed Elena and her coffin-bed from her hideout in Brooklyn, New York City, New York. So after switching the ownership to another human and having the new owner invite him inside the house, Stefan drives to Bonnie and Enzo's new house and attempts to kill Elena by forcing his way through. At first, Stefan extracts Enzo's heart from the front doorway, shocking Bonnie. As Stefan approaches a shocked Bonnie inside the house, Bonnie scrambles to find a weapon of last-minute choosing. Stefan scoffs at her as she attempts to use a wooden coach hanger as a weapon. He grabs her arm forcefully and slowly twists it as he mocks her for trying to protect Elena, but Bonnie mentions through her teeth that she is going to turn him into a human. Bonnie then injects Stefan with a dosage of the cure and this makes Stefan fall unconscious. While doing this, Bonnie is in tears at the death of Enzo, from Stefan's hands.
- Stefan: "Excuse me. Hi."
- Bonnie: "Hi."
- Stefan: "Um, have you guys seen Elena?"
- Bonnie: "I think she went home. I'm gonna give you Elena's cell number and her email. She is big on texting, and you can tell her... "I said so"."
- Stefan: "Thank you."
- -- Pilot
- Stefan: "Bonnie! Bonnie! Bonnie! Hey."
- Bonnie: "What just happened?"
- Stefan: "You were in some kind of a trance."
- Bonnie: "Did I do this?"
- Stefan: "I think so, yes."
- Bonnie: "Elena is my best friend, and because she loves you I couldn’t let you or Damon die in that fire."
- Stefan: "I'm very grateful Bonnie, I hope you know that."
- Bonnie: "I do, but I hope you know that things have to change. Damon has to change."
- Stefan: "We both want the same thing."
- Bonnie: "We both want to protect the people we care about. The difference is for you, Damon is one of them. You saw what I was able to do tonight. I know who I am now. If Damon spills, so much as one drop of innocent blood, I'll take him down...even if I have to take you with him."
- Stefan: "Let's hope it doesn't come to that."
- Bonnie: "Let's hope it doesn't..."
- Stefan: "What's the matter? Are you okay?"
- Bonnie: "When I touched him, I saw something."
- Stefan: "What do you mean? Like a vision?"
- -- Plan B
- Bonnie: "I know you love Elena and you wanna be with her, but it's risky. Too many people can get hurt."
- Stefan: "Look, I want Elena back, yes, but it's more than that. I mean, what Katherine did to Jenna, it crossed a line. She has to be stopped before it happens again."
- Bonnie: "I don't know, Stefan."
- Stefan: "Look, Katherine knows me, right? She knows that I'm not gonna try something in a crowd full of innocent people. So that gives me an edge. I can catch her by surprise."
- Bonnie: "I could do a spell to trap her. Like the tomb spell."
- Stefan: "Right. We can isolate her away from the others. Please, Bonnie."
- Bonnie: "Okay."
- -- Masquerade
- Stefan: "Are you okay?"
- Bonnie: "It didn't work. I’m not strong enough. Even with help I can't do it."
- Bonnie: "Then we need to go. Now. Before Jenna's been sacrificed. I can kill Klaus myself."
- Stefan: "Bonnie... If you use that much power, you'll be dead. We've already been through this. It's not an option."
- Bonnie: "Neither is letting Jenna die."
- Bonnie: "I'm not sure this is going to work."
- Stefan: "You've done a séance before, right? Contacted Emily Bennett? Maybe one of the witches might know how to help Damon."
- Bonnie: "Let's just hope they want to."
- Stefan: "Hello Bonnie."
- Bonnie: "Stefan! You followed me here?"
- Stefan: "Yeah. It wasn't too hard. You should probably be more careful."
- Bonnie: "What do you want with me?"
- Stefan: "Relax! I just need your help."
- Bonnie: "Why would I help you? Elena said you saved Klaus's life.
- Stefan: "Let me fill you in on a little secret about Klaus. He kept his family with him at all times, daggered, stored in coffins, and now I have them and I need you to help keep them hidden."
- Bonnie: "Are you out of your mind? You're just gonna make him angrier."
- Stefan: "His family is his one weakness. As long as I have that, I can ruin him."
- Bonnie: "I don't have enough power to hide four originals!"
- Stefan: "You're a witch, you hate Klaus, and I can figure something out."
- -- The New Deal
- Bonnie: "This can't be happening."
- Stefan: "Please tell me that you figured out a way to bring us all back."
- Bonnie: "I lost it, I'm sorry."
- Technically, both Stefan and Bonnie are natural enemies being he is a vampire and she is a witch.
- Stefan knew Bonnie's ancestor, Emily Bennett.
- Stefan has also spoken to Emily through Bonnie being Emily was able to possess Bonnie.
- Stefan has met most of Bonnie's close and distant, Bennett relatives.
- Both Bonnie and Stefan have been enemies with Klaus Mikaelson.
- They are currently working together to save Damon and Enzo from Sybil, the Armory's monster.
- They have worked together numerous of times to stop a common enemy in the past (e.g. Klaus, Silas, etc.)
- Bonnie used the Cure from Elena's body on Stefan, which turned him back into a human.