When Gabrielle first meets the Warrior Princess, Xena, she is a farm girl living in the village of Potidaea. She and her sister Lila, along with several other village girls, have been kidnapped by the men of the warlord, Draco, to be sold as slaves. Xena intervenes and rescues them. Awed by her fighting skills, Gabrielle decides that she wants to become a warrior too. She also wants to avoid the marriage that her parents, Herodotus and Hecuba, have arranged for her with her childhood friend Perdicas. Gabrielle insists on following an initially reluctant Xena on the road. The two women soon develop a strong bond of love and friendship. Over the six years of the series, Gabrielle evolves from a naive, idealistic teenager into a fully fledged, but deeply conflicted warrior fighting alongside Xena.
Gabrielle becomes an Amazon when she defends a dying Amazon Princess during an ambush. Before she dies, the Princess Terreis passes her "right of caste" to Gabrielle, and Gabrielle inherits her rank and possessions. This leaves Gabrielle the heiress presumptive to the Amazon Queen, Melosa. Melosa's adopted daughter Velasca, becomes a rival for the position of Queen of the Amazons after Melosa's death, but Velasca's schemes (which include aspirations to godhood) are foiled by Xena and Gabrielle. As Gabrielle wishes to travel with Xena rather than rule the Amazons, she appoints her friend Ephiny to act as Amazon Queen in her place.
Gabrielle learns how to fight with a fighting staff from the Amazons. With Xena's encouragement, she develops a philosophy of fighting for the Greater Good without killing.
About a year after meeting Xena, Gabrielle encounters Perdicas again and decides to marry him. The morning after their wedding, he is murdered by Xena's nemesis, Callisto. Gabrielle's grief and anger tests her ideals of reverence for life, but she nonetheless resists the impulse to kill Callisto. During this period, Gabrielle's strong commitment to peacemaking and compassion often serves as a counterbalance to Xena's warrior nature.
When helping to defend Britannia against Caesar, Gabrielle comes into contact with an evil cult that tricks her into killing one of its priestesses, Meridian. The loss of Gabrielle's "blood innocence" enables the evil god Dahak to impregnate her. After a pregnancy that lasts only a few days, Gabrielle gives birth to a girl she names Hope. After becoming convinced that the baby is simply a vessel for Dahak, Xena wants to kill Hope. Gabrielle manages to save her daughter by putting her in a basket and sending her downriver.
Several months later, Gabrielle finds Hope again, now looking like a nine-year-old, and already in the process of helping her father, Dahak, implement his plan to take over the world. Hope allies herself with Xena's enemy, Callisto. In revenge for Xena's attempt to kill her as a baby, Hope murders Xena's son, Solan. This forces Gabrielle to accept that Hope is indeed evil. She kills her daughter by giving her poison, an act that continues to haunt Gabrielle throughout the series. She holds herself responsible for Solan's death, as well as for betraying Xena a second time, even after reconciliation with Xena is effected through their musical journey in the Land of Illusia. When she once again encounters Hope, who was saved from the funeral pyre by her father, Gabrielle sacrifices herself to save Xena by jumping into a lava pit and taking Hope with her. Gabrielle mysteriously survives the fall, and is later reunited with Xena. It is later revealed that Ares saved Gabrielle, with plans to use her as a bargaining chip against Xena.
After her first kill, and the traumatic events with Hope that followed it, Gabrielle temporarily embraces complete pacifism as an alternative to fighting by Xena's side. She and Xena travel barefoot on pilgrimage to India, where they encounter a series of false prophets and gurus, as well as a genuine healer and teacher, Eli. Eli claims to have found enlightenment and Gabrielle becomes interested in his philosophy of non-violence and inner peace, which he calls the Way of Love. Gabrielle attempts to follow Eli's way, and throws away her staff under his influence. However, when Xena is in the midst of a battle with the Romans in an effort to rescue Gabrielle, Eli, and a group of prisoners, Callisto, uses Xena's own chakram against her, breaking her back. Gabrielle chooses to fight to save Xena and even kills some of the soldiers herself. Before their crucifixion, Gabrielle tells Xena that she had chosen "The Way of Friendship".
After being crucified, Gabrielle and Xena ascend into Heaven, but are soon ambushed by demons. The demons are able to take Gabrielle to Hell, where she comes face to face with the demonic form of Callisto. Xena and a group of Archangels are able to rescue Gabrielle from Hell before Gabrielle can fall to the darkness. She then learns that Xena has taken Callisto's place in Hell. She eventually forgives Callisto for the murder of Perdicas, and that act of forgiveness grants her the right to join the Archangels in battle. During her fight with the demon-Xena, they are restored to life by Eli.
At this time, Gabrielle accepts her new path as a warrior and acquires a pair of sai, which become her signature weapon thereafter. Xena's pregnancy, revealed shortly after the duo's return to life, further forces Gabrielle to fight and sometimes protect Xena. On two occasions, the god of war Ares, impressed by Gabrielle's new warrior skills, tries to recruit her to his side, but Gabrielle always resists.
Gabrielle and Xena sleep in an ice cave for 25 years after Ares places them there because he mistakenly believes they are dead. After waking up, Gabrielle discovers that her parents have been killed by the North African warlord Gurkhan, who has also kidnapped her niece, Sara, for his harem. Around this time, Gabrielle develops a close friendship with Joxer's eldest son Virgil, who shares many of her traits as a bard and warrior. Gabrielle struggles with the issue of seeking vengeance against Gurkhan. She is often troubled by her role as a warrior, particularly when she has to lead her Amazon tribe into a high-casualty battle against a superior army, led by the demigod Bellerophon, to rescue a fellow Amazon queen. Despite the success of the mission, Gabrielle tells Xena, "With each battle, I lose more of myself".
The series' final scene finds her on a ship headed to Egypt, where she intends to continue the fight for the Greater Good, with Xena accompanying her in spirit.
Gabrielle starts the series as a young girl who more or less stands behind Xena, and relies on Xena to protect her. In the course of 10 episodes, she acquires a fighting staff from the Greek Amazons and is a decent fighter with it shortly after. Another 10 episodes later, she displays immensely impressive skills with the staff, taking on numerous soldiers single-handedly, in the attempts to rescue Xena's presumably dead body. Probably what is most impressive, is that two episodes later she blocks an arrow in flight with her staff.
As time goes on, we see Gabrielle not only improve with her abilities with the staff, but as a total warrior as well. As she adds kicks, and minor acrobatics to her fighting, rolling over a hunched over opponent before proceeding to beat them.