Heidi was born in the 1520's in Germany. She was very beautiful, happy, adoring, and kind to others, allowing men to come after her. Heidi was wise to avoid them, but the only thing she liked was spending time with children. She always took care, and loved children as her playthings when she grew up as a maid. After the death of her parents, Heidi took her responsibility of taking care of her baby brother. Heidi always watched her brother and never let him go. She would take him somewhere around the country, exploring the wilderness around when the sun is bright, and enjoy a peaceful life. Everything changed after that.
After Heidi turned 26, she met a young woman named Hilda who was revealed to be a vampire. Hilda saw how beautiful she was, and she decided to offer her a gift of immortality. Heidi accepted her offer, and promised to look after her brother and protect him from harm. She was turned into a vampire, but after her transformation, she nearly killed her little brother when he hurt himself. Heidi was able to resist the thirst, knowing that she couldn't hurt her brother. Heidi feared that if she stayed close with her brother, she would get his life in danger by vampires, so it was time to let him go. Her brother was taken care by a peaceful foster family, and wished her brother goodbye. Heidi knew that she would never see him again, and this was the only part that she had to do.
Spending more than a century with the coven of vampires, Heidi started to get use with her mates, and spend time hunting Humans. Heidi chose to feed on the elderly instead of the young since she suffered memories when she nearly killed her brother and how she truly loved children.
This was when the Volturi accused Hilda and her coven for treason. Hilda begged Aro to spare her coven mates and allow herself to die for the guilt she did. Right after Hilda was "executed", Aro decided that Heidi was penitent and spared her, allowing Chelsea to then bound her to the Volturi and made her betray her coven mates. He decided to keep her as one of the guards while he allowed the rest of the coven mates to leave and run into hiding from the Volturi. Heidi became bound to the Volturi and betrayed her coven mates. Her main responsibility in the Volturi is arranging elaborate ploys to bring elderly human victims that are in their 60s, 70s, or 80s to Volterra. She is required to bring them from far away, without leaving a trail.
In the 21st century, Heidi always took a break when she is absent from Volterra. Knowing that her job is to lure elderly victims, Heidi went on to arrange an all-expenses-paid vacation to any random location, such as Hawaii. There, she would do an interview for a position with an amazing salary and bring tourists to have fun. She would also greet a lot of families, including their children, and take them to the rightful hotels with a couple of tours. Heidi enjoys her job, but she would be forced to do her part in luring victims to the Volturi. Once she sees elderly humans, she can use her power to make them unable to resist any invitation she extends. The victims never hear the word Volterra, and usually are unaware that they are even being brought to Italy.
After an interview, Heidi was present in a five-star hotel where she greets a young nine-year old boy named Freddy Brooks who was with his grand-parents. Reminding him of her brother, Heidi spends time with him in the hotel until she received a call from Chelsea. Chelsea orders her to start fishing in humans to their masters. Since she was bound by her gift, Heidi was forced to do so and began to use her gift on the elderly, but she didn't use it on Freddy's grand-parents since she didn't want him to be alone. Before leaving in her private jet, Freddy followed her and wanted to wish her goodbye when he gave her a necklace.
Heidi makes a brief appearance in New Moon, where she lures a group of elderly tourists into the Volturi's lair to be preyed upon by their members. Demetri, who is leading Bella, Edward and Alice to the lobby after their brief confrontation, tells her to save one for him. While making her way across the hall, she gives a curious look to Bella and Edward before entering the chamber to feast.
When the Volturi come to Forks for the immortal child crisis after mistaking Renesmee Cullen for being one, Heidi was not present since she was busy doing an interview in Las Vegas.
After the second confrontation between the Volturi and the British Coven, Heidi fled from Volterra, knowing that Chelsea was dead and free from her power. She moved to England where she offered her service to Gabriel. It took a while for Heidi to get use to drinking animal and human blood at the same time.