Cassandra is the daughter of Corona's Captain of the Guards. She is a skilled fighter who dreams of joining the royal guard, though she currently — and contently — serves as Rapunzel's lady-in-waiting and closest confidante, alongside the princess' pet chameleon Pascal. Her role generally requires that she assist Rapunzel in any means necessary. She also played an instrumental role in the return of Rapunzel's 70-feet of magic, golden hair.
Cassandra is described as being "tough-as-nails", a fitting description for someone who wishes to join the royal guard. She is snarky, sarcastic and has a somewhat dry sense of humor. Despite this, she is extremely supportive and protective toward Rapunzel, her polar opposite—so much so, that she openly holds animosity for Eugene, believing him to be selfish and undeserving of Rapunzel's love and friendship. One of the reasons for this belief is because she feels that Eugene puts his own desires before Rapunzel's, which she expresses to Eugene.
Although loyal to King Frederic and Queen Arianna, Cassandra is willing to break their rules (and risk her job) for the sake of Rapunzel's happiness; this is seen when Cassandra offered to take Rapunzel beyond the kingdom's wall to explore some of the outside world and escape the pressures of royalty. Doing so required much stealth and cunning, traits Cassandra revealed herself to have that night.
Aside from her no-nonsense persona, Cassandra is also a free-spirit, not unlike Rapunzel. Though she has a more cynical way of going about life, Cassandra also finds joy in adventure, living life to the fullest, and experiencing new things. This is most notably seen during "Wind in My Hair", where Cassandra is seen enjoying herself almost as much as Rapunzel.
Cassandra is first seen waiting for Rapunzel's return from a ride with Eugene at Corona's village gates. From there, Cassandra takes Rapunzel to attend to the various duties of a princess, specifically in preparation for her upcoming coronation ceremony to officially crown her as heir to the throne. Rapunzel laments her feelings of stress of the pressures of royalty overwhelm her. Cassandra believes the princess should take a break regardless of what her father wishes, but Rapunzel refuses to do so. Later at a dinner event, Cassandra sits with Pascal, while Rapunzel sits with her parents, and Eugene sits at the children's table (an arrangement made by Cassandra, who was in charge of seating). Eugene takes the time to propose to Rapunzel, but due to her fears of being bound to life in the castle, Rapunzel rejects and leaves. Seeing the princess upset angers Cassandra, who glares at Eugene.
That night, Rapunzel agrees to relieve her built-up tension by following Cassandra beyond Corona's border wall to explore the outside world for the night. Cassandra gears up for the adventure, providing Rapunzel with a hooded cloak and the two sneak their way out through a hidden passageway. They journey through the night forest, until Cassandra takes Rapunzel to a specific spot where the golden flower that saved Queen Arianna and the yet-to-be-born Rapunzel was grown. Suddenly, a blast of magic hits the two that causes Rapunzel's magic, golden hair to return.
The two return to the castle where Cassandra tries desperately to cut the hair. Like the rocks, it's unbreakable. When Eugene arrives, an anxious Cassandra urges Rapunzel not to tell him about the hair, fearing he'll tell the king and queen, which would cost Cassandra her job. He discovers regardless, but the three agree to keep it a secret from everyone else, including Rapunzel's parents. What Eugene still doesn't know, however, is how the hair came to be again. Cassandra refuses to tell him, and when confronted about her behavior towards him, Eugene discovers that his unintentional selfishness in regards to Rapunzel is partially to blame.
At Rapunzel's coronation, the hair is kept hidden beneath a wig, only to be revealed when she needs to utilize it as a weapon to fight off a band of thieves. While Rapunzel and Eugene fight off the goons, Cassandra takes on their leader Lady Caine. Caine is defeated and arrested for her crimes, though Rapunzel is reprimanded by King Frederic for the hair but Cassandra's part in restoring it was left out by Rapunzel.
In the perimere episode of the series, "What the Hair?!", Cassandra is first seen helping Rapunzuel fix her hair when they talk about Rapunzel's nightmare, where Gothel appeared and the spikes they saw in the movie surrounded her. Cassandra tries to calm her down, but Rapunzel wants to tell Eugene. Cassandra says no, seeing as she does not trust him and does not want to get fired.
- Interestingly, Cassandra's will to protect Rapunzel at all costs is also quite damaging, specifically with the relationship Rapunzel shares with Eugene. Because of Cassandra's distrust toward Eugene, the former actively advises Rapunzel to keep secrets from him, which in turn cripples the amount of trust shared between the two; though Cassandra blames Eugene for failing to address Rapunzel's personal struggles, it is impossible for him to do so if Rapunzel refuses to be honest with him. Though Rapunzel is at fault for choosing to keep secrets, Cassandra is also at fault for encouraging the princess' will to do so.