It should also be noted that, as a trained slayer, Erin can block Vlad's telepathy and can't be put into a trance. She can also slightly resist the control of the Rings of Arianrhod.
Series 3Erin is a new character added during the first episode of series 3. Erin arrives in the Dracula household having saved a sick Ingrid from the slayers guild who have been hunting her down to find Vlad. She has a plan to slay the Draculas whilst pretending to be turning into a vampire (half fang) by using stasis spray which hides her breathing and pulse rate from vampires. This plan does not come to succeed as she starts to fall for Vlad and by the end of the thrid series is fully in love with him. By the end it is discovered that she is not a true vampire but a slayer and her motives are known. She later abandons her plan to slay the Draculas and actually helps them occassionally.
Series 4Erin still lives with the Draculas. Ramanga and the Count are plotting to make Vlad abandon his hopes for peace between vampires and breathers. They eventually agree that the best way to do so is to take Erin out of the picture. The Count has tried killing her before but they decide to arrange for Vlad to marry Adze, Ramanga's daughter. Vlad, Jonno, Bertrand and Erin try to stop the wedding.
After thinking she received a visit from Ryan's ghost, she tries to kill the Count. He easily catches her and was going to kill her until Vlad intervened. She left after this with a broken heart saying that Vlad could only have peace in his work if he married Adze. As she left a figure followed her.
In the next episode it emerges that Erin was kidnapped by the Ramangas to be the wedding breakfast. When she emerges from the coffin she was imprisoned in and threatens to slay Adze with a UV torch, Adze is confused because Ramanga was supposed to have put Erin in a trance but it didn't work. Before Erin can act, Ramanga saves his daughter, putting Erin in a trance once again but it quickly wears off or Erin was pretending to be in one.
Erin is fatally wounded when Adze throws a fireball at her after the rings of Arianrhod fail and she tells Vlad not to bite Adze.
Vlad catches her as she falls from the roof.
As Erin was going to die, Vlad was forced to bite her, turning her into a vampire, and Erin ends up hating him.