Hayley has long, light brown hair tied up in a ponytail. Her eyes are blue and her skin is light. She wears a white T-shirt and golden earrings.
Coming off as innocent and oblivious, in reality Hayley is a manipulative murderer who uses her pop-star act to cover up who she really is. Prone to jealousy and lashing out, she is willing to do anything to protect her reputation.
Hayley was originally from Dent County, Missouri where she lived with her father, John Tull, among a number of other unnamed individuals. Having a rough lifestyle she was dissatisfied with her life in Missouri, dreaming of leaving for California. When she was 18 years old her boyfriend cheated on her, leading to her stabbing him to death with a broken bottle. Her father was caught with the body when he was on his way to dispose of it but took the fall for her. Using this as an opportunity to escape, she ran away to L.A. where she met Jamie Brooks at an open mic. Knowing that she'd likely have little success if the public new about her true origins, they developed a new personality for her; Hayley Rose who was raised by her grandmother in Palos Verdes.
When Gavin Routh leaked her childhood photos, Hayley realized that people would become more interested in her background and delve deeper into her life, potentially exposing her true father's identity and consequently discovering that she killed her ex-boyfriend in Missouri. To protect her reputation, she sent Tull to kill Gavin and Jessica Greene.
After matching a photo found in John Tull's trailer to a recovered photo of Hayley as a child, Samantha Massey and Dave Reyes discovered that John is Hayley's father. He was overly protective of his daughter, going to extreme lengths to protect her such as taking the fall for a murder she committed and eliminating those who threatened her reputation and career.
Jamie Brooks was Hayley's agent. After watching her perform at an open mic, he signed her as his client and paved her way to stardom under the false persona of 'Hayley Rose'. Once she became a renowned pop star he embezzled money from her, resulting in him being targeted by Tull. He work with Alyssa Griffin to help her transition from acting to music may have sparked some jealousy and possessiveness.
- Although she does not make an appearance, her song "Outlaw", which was a key plot point in Most Wanted, Book 1, is mentioned in Endless Summer, Book 1 and The Freshman, Book 3, when you talk to Amara during Madison's Party.
- In Endless Summer, Book 1, Chapter 13, it is referenced that her killer may have been a Cultist.