She had pale skin that her blue veins could be seen and wore a long white dress. She was described as young, with a physical appearance of a twenty something. She had oddly titled, large, light blue eyes, red lips and long black hair that went past her shoulders. She was also described as being tall and elegant.
She had shown to have no remorse for the killing she's responsible for and is described as being malicious. She even openly mocked Elena in the movie theater in what's described as a "ta ta" gesture while wiping blood off her mouth with the other hand. She also acts in a somewhat childlike behavior, and is shown to be intelligent and cunning. She holds a grudge against Jack for what he did to her, and has vowed to kill him.
- Siobhan is the Irish version of Jehanne and means "God's grace".
The Salvation Series
The Guardians revealed to Elena that she needed to hunt and kill an ancient and powerful vampire, who, unlike the Old Ones, has not grown to be more humane during the time she has spent roaming the earth and is a very clever woman who will kill without remorse.
She is first seen in a dream by Elena and afterwards, she encounters the vampire who has fed on a couple and killed them in a movie theater. She disappears after feeding and giving Elena a "ta ta" gesture while wiping blood off her mouth. It's also revealed that Siobhan was responsible for killing Jack's wife, Lucia.
After traveling in the Appalachians, Elena and Damon find her surrounded by a bunch of corpses, while still feeding on another victim. She notices the two and when Elena asks for her help in defeating Jack, she heads straight towards Elena and grabs her by the throat. When Damon mentions Jack's real name, Henrik Goetsch, she lets go of Elena and is asked what she remembers about him. She tells them that he tricked, trapped and pretended to love her, and he used her blood to create his artificial vampires. She also reveals that she has the poison that can kill not just the artificial vampires, but Jack as well. At first, she wants to kill the two as she wants to kill Jack on her own. She asks to come with them and they take her with them in the car, complaining about the ride in the process. They meet up with Meredith and Jasmine, and at first she doesn't want to give the vial over, but eventually does give it to Damon.
The group goes to battle with the vampires inside and with a cold and expressionless face, Siobhan steps on a vampire, cracking a rib. After Damon attacks Jack, Siobhan is noticed by him and she greets him. When Damon injects the poison in him, Jack has a reaction, but doesn't die, and Damon is staked through the ribs. Siobhan reveals to him that she wouldn't give him the true poison as she loves Jack and wants to kill him herself. She is staked through the heart by Elena, which kills her in the process.
- Elena referred to her as looking like Snow White, a fairytale character created by The Brothers Grimm.