- "Relax, Zach. You're going to get wrinkles. Damon's not going to come to Mystic Falls. Besides, even if he does decide to show up, I'll know it before he even thinks about returning. Don't tell me you've forgotten that your favourite distant aunt has a special talent of seeing into the future?"
- —Ellie puts Zach's mind at ease.
Ellie is first introduced into the series as the younger sister to Stefan Salvatore, both of whom recently move into the town of Mystic Falls, and enroll as a student at Mystic Falls High School. She currently lives her nephew Zach (along with Stefan) in the Salvatore Boarding House. Zach refers to her as "Aunt Ellie", even though Ellie looks significantly much younger.
Zach was not impressed with the visit of Stefan as he knew Damon would surely follow, due to the fact that he had promised Stefan an eternity of misery. Ellie assured Zach that she would be on the lookout for Damon, and would let him know if she had a vision of his return. It is suggested that Zach trusts Ellie the most out of her siblings due to her kind hearted and compassionate nature.
Ellie wears a small, almost delicate, silver ring made from enchanted Lapiz Lazuli stone (a stone which was enhanced by Emily Bennett back in 1864) that allows her to walk around in the sunlight without burning. Unlike Damon, who drinks human blood and feeds off of innocent people, Ellie has chosen to stuck to a vegetarian diet. While feeding on animal blood has its disadvantages (as vampires who feed on human blood are generally stronger), Ellie has the upper hand due to her gift of foresight.
It is at the high school that her brother, Stefan, inevitably and fatefully meets Elena Gilbert, who bears an unusual, and striking uncanny physical resemblance to Stefan's past love from 1864, Katherine Pierce. Due to her experience with Katherine, Ellie became wary of Elena as she did not want this to turn into another love riot. However, over a gradual period of time, and after Stefan introduces Elena to Ellie, she is quickly to realize that Elena is nothing like her doppelganger. She has a few positive visions of Stefan and Elena being together, and becomes very friendly and bubbly towards Elena. Stefan warns Ellie to not frighten Elena, to which Ellie replies that Elena is going to find out the truth, sooner or later. At Mystic Falls High School, Ellie befriends Caroline, whom takes a strong liking to Ellie due to her bubbly personality and interest for fashion. Caroline comments that Ellie is like "the sister she never had."
- Damon: "And how is my favourite baby sister?"
- Ellie: "I'm your only sister, Damon."
- Damon: "Precisely, which makes you my favourite."
- — Damon and Ellie's reunion.
Just as Zach feared, the arrival of Stefan resulted in the arrival of Ellie's and Stefan's older brother, Damon Salvatore. Upon his arrival, Damon uses his time to torment Stefan by constantly threatening Elena. Ellie is not pleased with Damon's behavior and warns him to leave Stefan alone and let Elena be. While Damon ignores Ellie's warnings, and continuously torments Stefan, he seems to take a more lighter approach towards Ellie, claiming that he missed his "favorite baby sister".
When it became clear that Damon was only going to be a problem, Zach revealed to Stefan that he had been growing vervain secretly in the basement. He offers to give it to Stefan in hopes that he would be able to weaken Damon, thus gaining the upper hand. Ellie warns Stefan not to spike Damon's drink, and to instead spike Caroline's drink (as Damon had been using her as a human blood bag). Nevertheless, Stefan attempted to drug Damon by mixing the vervain in his drink, but Damon was able to detect the vervain in his alcohol. Annoyed at Stefan for not listening to her warning, Ellie reminds him to take more vervain to the Founders Party, and to spike Caroline's drink.At the party, Ellie is invited into the Lockwood Mansion by Carol Lockwood. At the display room, Elena reads the first guest registry for the First Founder's Party and see's Damon, Stefan and Ellie's name on the list. Ellie keeps a close eye on Damon, and accepts his dance request, thus allowing Stefan to spike Caroline's drink with vervain.
Later, Damon seems to blend into the party until Elena sees the bites on Caroline’s back and confronts him, threatening to go to Caroline’s mother. Angered by this, Damon takes Caroline out near the lake. He claims to forgive her, but then says he’s over her and bites her neck. He didn't realize that Stefan had spiked her drink while dancing with her, and that he’d just consumed enough vervain to render him harmless. Stefan and Ellie took him back to the Salvatore mansion, injected him with more vervain, and locked him in the dungeon under their home. Damon does not stay locked in the cellar for long, as he uses what little mind control he had left over Caroline to compel her to free him.
When Elena discovered that Stefan, Damon and Ellie were vampires, it caused her to become hostile and fearful towards all of them. Because of her kind hearted nature, Stefan asks Ellie to speak with Elena. She meets up with Elena, and assures Elena that she has nothing to be afraid of, that Stefan loves her and allowing any type of harm to come her way would be the last thing on Stefan's mind. Ellie also mentions to Elena that she won't be fearful of them for long, as she has "seen" Stefan and Elena being happy together.
It is then that Ellie tells Elena that she has visions of the future. She can't always choose to see what she wants to see,, though her visions are always precise and have never been wrong before. While Elena is both shocked and overwhelmed by the information she was finding out as the days went on, her trust towards the Salvatore siblings was put on good terms when they saved her from being injured by Vicki Donovan, Matt's older sister and Jeremy's new girlfriend, who had been turned into a vampire by Damon the night before.
When Vicki escaped the Salvatore Boarding House at nightfall, Ellie used her visions to track Vicki, and saw that she planned to hang out with Jeremy at the school's Halloween party. Dressing up as a devil, Ellie joins Stefan and Elena's search for Vicki, knowing that her lack of control over her blood lust would only result in death. Stefan ultimately killed Vicki when she bit Elena, attempting to drink her blood to kill her at the school's Halloween party.
In "Bloodlines" it was revealed that Stefan had saved Elena from the car crash that killed her parents after Ellie informed him of a vision she had of the event, but believed it to be Katherine.
In "Unpleasantville", a pizza guy came and Jeremy invited him inside, unaware that he was Noah, a vampire who was trying to gain access to the Gilbert's house. He almost attacked Elena while she was getting ready for the dance, but the Gilbert Compass alerted her to his presence, and Stefan showed up just in time to scare him off.Ellie is called, alongside Damon, where Stefan asks her if she could get a vision on Elena's attacker. It is there that Elena witnesses for the first time Ellie receiving a vision. While experiencing the vision, Ellie is quickly draws the scene she "see's" in her vision without looking, and also rather quickly. Her vision shows that Elena's stalker will be expecting her at the 50's Decade Dance. Just as predicted, Elena's stalker showed up at the 50's decade dance. He attempted to attack Elena, but was stopped by Stefan and Damon.