When she meets Stefan Salvatore, she starts to falls in love with him. But, due to his lies and past history with his brother, Damon, she starts to mistrust him. When she learns that Stefan was in Mystic Falls in 1953, she confronts him and learns that he is a century-old vampire and that this is the reason why he is so estranged with Damon, who is also a vampire. After a period of tension between them, Stefan and Elena get back together. Also, despite the fact that she abhors his human-hunter instincts, she develops a tense friendship with Damon himself. And later on in the series, she finds out that Damon is actually in love with her and Stefan tells him that history will not be repeating itself where Elena is concerned.
After some time, Elena discovers several secrets about herself: first, she is the spitting image of Katherine Pierce, the vampire both Salvatore brothers loved and who turned them into vampires; second, Stefan saved her from the car accident that killed her parents; and third, she was adopted by the Gilbert's. Her birth mother is Isobel Flemming-Saltzman and she doesn't know who her father is. She later learns that Damon turned her mother into a vampire at her own request. Also, in a scene of the series where Isobel and Johnathan were talking over the phone, it was known that John Gilbert, who she thought was just her uncle who causes a lot of trouble to their family, is actually her real father. Her brother, Jeremy has decided to turn into a vampire after Anna dies and he doesn't want to feel pain anymore. So he drinks a vile of blood Anna gave him and then takes sleeping pills. It seemed as though Elena and Damon kissed however it was Katherine. This was later revealed when "Elena" cut off John's fingers (with the ring on it) and stabbed him. Right before she killed him, he realized "Elena" was Katherine.