|“||Oh, don't worry ghost kid, it won't hurt long, BECAUSE YOU ARE GOING DOWN!||„|
She was once a rich, popular girl at Casper High, and part of the "in" crowd with Paulina Sanchez, Dash Baxter, Kwan , etc. Until the appearance of a huge ghost dog at Axion, a large laboratory facility where her father worked, appeared. Danny tried to catch the dog (which could shapeshift from a harmless puppy to a huge monstrous form that Danny calls Cujo) but the two of them cause so much ruckus and damage, that her father, Damon Gray, loses his job. He had been the chief security system designer for the facility, and the dog was ironically the ghost of one of the old guard dogs before the security system had been installed. Due to his job loss, she and her father have little money- and thus her popularity status from the "in-crowd" plummets. Valerie blames her misfortunes on Danny Phantom, thus dedicating herself to hunting ghosts.
Unbeknownst to her, Vlad Plasmius has taken advantage of her grudge and has secretly supplied her with various ghost-hunting weaponry with which to destroy Danny (and allow Vlad to spy on Danny in secret for his own misdeeds). She later learns her weapon supplier is Vlad (although she is unaware of Vlad's own alter-ego as Plasmius) and believes him to be a good man and fellow ghost hunter who recognizes her talents. By "Reign Storm", Valerie gains a friendship and later crush on Danny Fenton.
In "The Ultimate Enemy", her future self has become Amity Park's defender. When Dark Danny broke Amity Park's enhanced Ghost Shield, she tried to hunt him, but he easily sent her away. Though present Danny was able to prevent her form hitting the wall, she then fell dead. Before she died, she says she almost forgot how cute young Danny was. However, this future was canceled thanks to Clockwork.
In "Flirting with Disaster", Valerie and Danny date for a brief period of time to which Technus uses to his end; keeping the two occupied while he goes about his plans for world domination and possessing her armor in an attempt to kill him (and creating more cause for Valerie to hate Danny's alter ego). When Technus hooks up with a satellite in space, he upgrades Valerie's suit, giving her an advanced red and black-striped one, and the power to change into it at will (it can 'appear' and wrap itself around her whenever she wants). This was meant to further distract Danny from his own dastardly plans, as she was now even more dangerous to Danny Phantom then she was before.
In "D-Stabilized", Valerie is hired by Vlad to seek and capture Danielle "Dani" Phantom. Vlad tells her that Dani wants to destroy him. Using a ghost detector, she instead finds a human Danielle, and is unaware she is the same "Dani Phantom." When mistaken as a hostile situation, Danielle runs from Valerie into an unstable building about to collapse where she saves Valerie's life when the hunter followed and almost perished from within from falling debris. After exposing herself as a half-ghost, Valerie captures Danielle and uses her to lure out Danny Phantom (upon gaining knowledge of Danny's affiliation with her) to great success. She then ships her off to Vlad until Danny convinces Valerie that she is innocent, and half-human as well. Calling a temporary truce, the two work together to save her from Vlad Plasmius's clutches. By the end, Valerie discovers that Vlad Masters and "Plasmius" are one in the same, and vows to take him down as well.
She makes a final cameo appearance in "Phantom Planet". First she gets pushed aside by Vlad's "Masters' Blasters" team, and eventually takes part in saving the world from a deadly asteroid. At the end, she finds out who Danny Phantom and Danny Fenton are one in the same. It's unknown if she still hate Danny when she found out the truth.