Stefan and Valerie

This is the former romantic relationship between Stefan Salvatore and Valerie Tulle. They were having a child together before Lily Salvatore's ex-lover beat their unborn child until Valerie miscarried the fetus. They both want revenge on Julian for destroying any possibility of a normal future together. Their relationship is now complicated due to his feelings for Caroline, in present day.

Early History
Originally, Lillian Salvatore, Stefan's mom, asked and assigned Valerie to see how Stefan was doing after Lily's supposed-death. They met at a fair and immediately took a liking to each other. Julian tried to suppress their growing friendship and even romance, but their relationship eventually turned sexual. Later on, they planned to run away together, but Julian would not allow her to go. Julian beat her until she miscarried Stefan's conceived-child and forced her to come back with him to London, England. Stefan was left behind to believe that Valerie just used him and eventually moved on to Katherine Pierce when the doppelgänger came into Mystic Falls.

Season Seven
In Age of Innocence, Valerie originally tells her story of meeting Stefan to the Heretics' prisoner, Caroline Forbes. At the end of the episode, she reunites herself with Stefan by placing a cloaking spell on herself to tell him what really happened to her and that she didn't abandon him on purpose. Stefan is oblivious to this after Valerie explains her story to him on the bench they met by in Mystic Falls.

In I Carry Your Heart With Me, Caroline convinces Stefan, after a night together, to spend the day with Valerie to, "clear the 19th century drama." He eventually listens to her and spends the day with her and Damon trying to track down Julian. After they find him, Valerie attempts to kill his preserved body. However, the rest of the Heretics stop them. As revenge for Lily taking Julian away from Valerie to awaken/bring back to life and for Lily disowning Valerie for killing Oscar and trying to kill Julian, Valerie spitefully tells Damon, in front of Lily, that it was Lily's idea for Kai to link Elena and Bonnie's lives together and send Elena in a lifelong slumber until Bonnie dies. Damon was infuriated by this and almost kills Lily, but Beau comes to defend Lily and they take Julian away successfully to resurrect him. After Beau sent a typhoon-like blast in the warehouse they battled in, Damon, Valerie, and Stefan were blown into unconsciousness. When Stefan wakes up, he makes sure Damon is okay and doesn't go after Lily before he see some if Valerie is okay. While Stefan wakes Valerie up, she reveals to him finally that's she was carrying Stefan's child. Valerie also told Stefan that Julian is the reason for her miscarriage of their child. Stefan is sent into shock as they drove back to Mystic Falls together. Stefan later promises Valerie that they'll get to their revenge on Julian for killing their unborn child. Stefan decides to keep their unborn child a secret from everyone, including his girlfriend Caroline, which Valerie appreciates.

In Cold as Ice, it is shown that they are together (romantically, once again) in a flash forward and Valerie is worried for him when he briefly, but affectionately tell is her that he will be okay rescuing his brother and Caroline. However, in present day, they are still friends who attended their motherly figure's funeral together. They both tried to keep Damon from ruining the funeral procession with his sarcasm.

Trivia

 * Stefan lost his virginity to her 6 years, after his mother's "death".
 * Valerie was jealous of Caroline's romantic relationship with Stefan when she found out about their relationship.
 * They were having an unborn child together.
 * Stefan decides to honor Valerie's (and now his) secret that they were having an unborn child together.
 * He lied to Caroline for Valerie.