"I know how to keep a secret"
Cassidy hangs around with his older brother a lot, even though Dick victimizes him almost as much as his usual targets. Despite his unspoken reservations, Cassidy acts as an accomplice when Dick and his friend Logan Echolls cause trouble in the community.
Cassidy is extremely needy as a result of the emotional neglect he suffers at the hands of his father, who openly favors Dick over him. Eventually overcome with guilt, Dick reveals that he and his father would have contests to see which one could make Cassidy cry. Dick also admits to duct-taping Cassidy's feet to the pedals of his bike, forgetting about it and a couple of hours later found him pedaling around desperately in circles.
During Veronica's investigation of her rape at Shelly Pomroy's party, she discovers Dick had encouraged Cassidy to rape her while she was unconscious to lose his virginity. Cassidy, however, denies it. He tells Veronica that he ran out of the room and threw up, after realizing that he could not go through with it.
When his father marries a younger woman, Kendall Casablancas, Cassidy tells Veronica that he suspects she is having an affair and hires Veronica to find proof. In the process, Veronica exposes Cassidy's father's real estate scam. Cassidy's father quickly abandons his family and flees the country.
After being rebuffed in his request to move back in with his birth mother, Cassidy starts a new real estate business. With help from Cindy "Mac" Mackenzie as his tech girl, he creates a company named Phoenix Land Trust, using Kendall as the on-paper "owner" of the company as Cassidy is underage. The Trust buys up cheap properties outside the proposed borders for the City of Neptune, a risky move that bet heavily against passage of incorporation.
Cassidy and Mac soon begin dating, but their relationship falls apart when he refuses to become sexually intimate with her. When she mentions to Cassidy that she had gone to Veronica for advice, Cassidy abruptly dumps her for bringing Veronica into his personal life.
Cassidy was one of the boys molested by Woody Goodman. Veronica discovers that not only did Cassidy set up the bus crash to kill Woody's other victims (who intended to come forward) but he is also responsible for such other the events as orchestrating the exposure of his father's real estate fraud and Goodman's fall from public favor. She also discovers that he did rape her after all, giving her chlamydia in the process, which he had, in turn, contracted after being molested by Woody. After Cassidy blows up the plane bringing Goodman back to Neptune following his arrest, he tries to kill Veronica. Logan stops him, however, and Cassidy commits suicide by jumping off the roof of the Neptune Grand. (Not Pictured)
Some fans have interpreted Cassidy's characterization to mean he is also in fact gay.  Others interpreted it to mean that he was just traumatized after he got molested by Woody Goodman.
Evidence the writers intended Cassidy to be homosexual includes the following:
- His snide references to his brother and father's views of masculinity.
- His reluctance in being sexually intimate with Mac before they broke up.
- His rape of Veronica in a desperate attempt to prove his manhood.
- Dick tells Mac that she was just Cassidy's "beard."
- Two of the students on the bus, Marcos Oliveres, and Peter Ferrer, were both also molested by Woody Goodman and were both gay. The latter was also planning the "outing of all outings", most likely going public with Goodman's actions.
- Veronica alludes to him being gay when she confronts him about raping her: "It helped that I was unconscious, didn't it? You could imagine I was whatever you needed."
- Cassidy not being able to get an erection when in bed with Mac (this could be construed as being homosexual and not being aroused by Mac or as trauma from being molested). Also, he did not rape Mac.
- Veronica Mars
- Season One
- Season Two
- http://web.archive.org/20060511164515/www.afterelton.com/TV/2006/5/veronicamars.html The Good, the Bad, and the Gay on the Season Finale of Veronica Mars