When Veronica’s best friend was murdered, her father removed from the office of Sheriff for accusing the victim’s father of the crime, her mother abandoned the family, and her friends turned into foes virtually overnight, Veronica had to grow up quickly. She changed from a giggling teenage girl living a Seventeen magazine life to something from a Raymond Chandler novel fiercely protecting what remained of her family and carrying on the investigations of her best friend’s murder.
Veronica is sharp. She’s very intelligent, earning high enough marks during her high school career to be part of the running for a private scholarship that would have paid for an Ivy League education, and moreover, she’s observant. Like any good detective, she takes stock quickly and notices details to a degree most people do not. She’s also streetwise and has bravado in spades. While she often appears unflappable to her enemies, she usually ducks out of site to express her true emotions. She can become carried away by her feelings, though, and in conjunction with her lack of patience, she sometimes finds herself in over her head and in need of rescue.
Despite her tough-as-nails exterior, Veronica is still capable of being the charming, personable girl she was before her best friend’s murder (at least, when it behooves her to be). She’s also a convincing actress (especially if the role involves a tight sweater and a dim smile) and a skilled liar.
Additionally, Veronica is hardworking and diligent. Whether she’s digging into a case or just making cookies for a friend, she pushes herself to succeed, even to her own detriment. She doesn’t seek attention or recognition (unless it’s in the form of cash payment), and she fights hard for those suffering from the constant class warfare consuming her hometown, Neptune, California. She is kind to most, but can be cruel to those closest to her.
Before Lilly Kane was murdered, Veronica and she were basically sisters. Veronica dated Lilly’s brother, Duncan, and she, Lilly, Duncan, and Lilly’s boyfriend, Logan, were inseparable from junior high on up. Lilly and Duncan’s father’s company, Kane Software, had developed streaming video, and since Kane Software employs much of Neptune, the town’s citizens made money along with the Kanes. When Lilly was found murdered at the family’s home, and Veronica’s father - Neptune Sheriff, Keith Mars - accused Jake Kane of the murder, the entire town rose up against him and ran him out of office.
As a result, Keith Mars was forced to give up the family’s home and move to an apartment. Not only was Veronica grieving the loss of her best friend, she’d lost her home as well, and her former friends had turned against her, leaving her utterly alone. She no longer had contact with Lilly’s brother, Duncan, and Lilly’s boyfriend, Logan Echolls’ had made it a personal mission to hurt her, constantly taunting and harassing, and encouraging others to do the same.
A few months after Lilly’s murder, Veronica brazenly attended a party hosted by a classmate, and while there, she accidentally ingested GHB (thanks to another “friend” spitting into her drink), and she awoke the next morning sans panties and alone in a bed. She assumed she had been raped, and when she reported it to the Sheriff, he refused to help. Later, she found out she was raped by Cassidy Casablancas (and contracted chlamydia from him), and later that same night, engaged in consensual (if drugged) sex with Duncan Kane. Around the same time, a man was arrested for Lilly’s murder, and plead guilty to the crime, and soon after, Veronica’s mother left town.
During Veronica’s junior year of high school, she assisted her father at his detective agency and made additional cash by digging up dirt on the parents of her classmates, finding she had a real knack for working as a detective. She also resumed the investigation into Lilly’s murder, believing the man behind bars had taken the fall. Eventually, she found evidence in Lilly’s bedroom showing Lilly in an intimate relationship with Logan’s father, an A-list actor. Assuming her friend meant to blackmail Aaron Echolls with the information and Aaron was the murderer, she left the Kane’s with the intention of telling her father. Aaron had been hiding in Veronica’s car, and when he appeared in the rearview, Veronica wrecked the car, injuring both of them and knocking Veronica out.
When she came to, she headed for the nearest house, meaning to call the Sheriff’s department, but Aaron caught up to her, trapping her in a refrigerator outside. Keith, fearing his daughter was in trouble, turned up and engaged Aaron in a fight. Finally, Aaron was knocked out, and Keith freed Veronica.
During Veronica’s senior year of high school, a school bus full of Neptune high school students plummeted over the edge of a cliff. When a stuntman connected with Aaron and the bus crash turned up on the beach with Veronica’s name written on her hand, she believed the crash was meant to kill her (as she’d missed getting onto the bus earlier), so she made it her goal to discover who’d caused the crash and why.
Her investigations led her to uncover yet more dirt about her hometown - the mayor, Woody Goodman was a child molester who’d raped Cassidy Casablancas (yes, that was where Veronica got the Clap - small world), and Cassidy was so determined to keep it quiet, he caused the bus crash to permanently silence other victims.
She confronted Cassidy on the roof of a hotel, and upon detonating a bomb on Woody’s plane, he jumped to his death. Veronica had thought her father was on the plane, but luckily, he had not boarded and was safe. Very soon after, Veronica graduated from high school and rekindled a romantic relationship started the summer prior with Logan Echolls (whose father had been acquitted of Lilly’s murder, but killed by a hitman paid for by Duncan Kane).
This is the point I play Veronica from, though there is additional canonical history for her.