Like the series' other principal characters, Trinity is a computer programmer and a hacker who has escaped from the Matrix, a sophisticated computer program in which most of the human race is imprisoned. Though few specifics are revealed about her previous life inside the Matrix, we are told that Morpheus, one of a number of real-world hovercraft commanders, initially identified her and helped her escape from the program. At the beginning of the series, she is first mate on Morpheus' Nebuchadnezzar and serves mainly as a go-between for him and the individuals he wishes to free from the Matrix. As the series progresses, her primary importance as a character becomes her close relationship with Neo. She is skilled with computers, at operating vehicles both inside and outside the Matrix, and in martial arts.
Throughout the series, her name is never revealed and is only referred to as Trinity.
We first meet Trinity at the beginning of The Matrix, in a phone conversation with Cypher, which is heard offscreen. This cuts to a dingy hotel room a chase scene between Trinity and a group of police officers and Agents, a series of programs that police the Matrix against rebels.
Trinity is next seen communicating with Neo for Morpheus in several encounters. Eventually, she and the rest of the Nebuchadnezzar crew unplug Neo from the Matrix and begin his training as a new recruit in the war against the machines. She participates in several missions into the Matrix, including taking Neo to The Oracle, a computer program inside the Matrix who is said by the rebels to have supernatural powers.
Throughout the film, it is apparent that Trinity has developed romantic feelings for Neo. Near the end of the film, after he is killed by Agent Smith in the Matrix, she speaks to his still-plugged-in body and reveals that the Oracle told her that she would fall in love with The One, a prophesied individual with superpowers inside the Matrix. She insists that he can't be dead, because her love for him proves that he is, in fact, The One, then kisses him, whereupon he miraculously wakes up. Neo defeats the Agents and the film ends.This marks the beginning of a romantic relationship between Neo and Trinity which will prove decisive in the outcome of the series.
The Matrix Reloaded:
Trinity's importance as an individual character in the first sequel to The Matrix is fairly minimal for the first half of the film, though she appears in almost every scene. She aids in the rescue of the Keymaker from the Merovingian and in the subsequent escape, but her real role in the plot does not come into play until the climax of the story, where Neo is forced, at least ostensibly, to choose between saving Trinity and saving Zion, the underground city where the last humans not living in the Matrix reside. Motivated by his individual love for Trinity, where all of the five previous Ones were motivated by a profound general attachment to humanity as a whole, Neo chooses to save Trinity, and revives her after she is shot by an Agent.
The Matrix Revolutions:
In the final installment of the Matrix series, Trinity is involved in the rescue of Neo from a cut-off segment of the Matrix, where he is being held by a program in the employ of the Merovingian. Later, back in the real world, Trinity goes with Neo to the Machine City in an attempt to negotiate with the Machines. While attempting to evade Machine pursuers, their hovercraft crashes violently. Trinity is impaled in several places by power cables and dies shortly thereafter.
After Trinity's death, Neo finds the courage to make the final sacrifice for humanity, giving his life to defeat Smith and negotiate a truce with the Machines.
Throughout the Matrix franchise, Trinity, like the other Matrix hackers, is shown to be highly competent at many skills both inside and outside the Matrix, including martial arts, computer use, the use of firearms and other weapons, and operating a range of motor vehicles.
Trinity is seen to be especially skilled at the use of cars, motorcycles, and other vehicles, even in comparison to other hackers. In the first film, she pilots a Bell 212 helicopter and manages to maintain control even after its hydraulics system is damaged. In The Matrix Reloaded, she carries the Keymaker to safety on a Ducati 996 motorcycle in a harrowing chase through oncoming traffic.
Combat, both armed and unarmed, is another area where Trinity, like her fellow crew members, excels.