EVE functions as a biological terrestrial probe. Having all necessary parts of a probe droid. She has an ergonomically suitable shape, scanner, flight at high speeds to cross ground quickly and morphable fingers for purposes to mimic human dexterity in the manipulation of objects. EVE is also armed with a plasma cannon in her right arm. However, it is odd that a simple probe would have a plasma gun considering the planet she was sent to was uninhabitated. The weapon is presumably used for defensive use or demolition of obstacles in her way. An example of this is when she blasts away an electromagnet she is trapped by.
Dedicated to her mission in scanning for any signs of self-sustaining plant life on earth, EVE was not interested in WALL-E and was even hostile towards him at first, but befriended him when they formally introduced each other and when he took her to safety.
After WALL-E saves EVE from a dust storm, he takes her to his trailer and shows her all the treasures that he has collected over the years, including the plant that he found. EVE quickly recognizes the plant, scans it and uses a tractor beam to pull it into her chest cavity. EVE deactivates to a state in which only a blinking green beacon signals that she is on. Determined to protect EVE, he shelters her from rain, lightning, and more until the Axiom return vehicle picks her up to return her to the Axiom.
When EVE is back to Axiom, she is taken to the Captain for inspecting. After being reactivated, she discovers, to her surprise, that WALL-E had followed her back to the Axiom and tries to hide him. She then opens her chest cavity to show the Captain the plant, only to find it missing and angrily accuses WALL-E of stealing the plant, though WALL-E has no memory of the theft. The Captain deems EVE to be defective and calls GO-4 to have her taken to the ship's Repair Ward, along with WALL-E. Arriving the Repair Ward, EVE gets placed in a Diagnostics Room, separated from the main room by stained glass doors, while WALL-E is placed in a force field pen. Inside the Diagnostics Room, EVE is being gently taken care of, but WALL-E, who only can make out EVE's silhouette through the glass doors, mistakenly believes that she is being tortured from seeing her arm being detached and her being "beheaded." He frees himself from his pen, crashes through the glass doors, and grabs EVE's detached arm—equipped with a laser gun—threatening to shoot at the arms taking care of EVE unless they set her free, but EVE demands WALL-E to put down her arm. In a panic, WALL-E fires a single shot that blows up a control panel of the Repair Ward, causing the repairing robots to be shut down and setting all the other reject robots in the ward free. The rejects then lift WALL-E up, him still holding onto EVE's arm, as they leave the Repair Ward, with EVE, shocked at what has just happened and wanting her arm back, following after them. The robots are confronted by Steward Bots, who have been alerted to the rejects breaking free. EVE manages to catch up and regains her arm from WALL-E; in the process, one of the Steward Bots take a photo of WALL-E and EVE, identifying them as "rogue robots." After losing the robots, EVE sends WALL-E to the ship's escape pod bay, where she activates one of the pods and coordinates it to go back to Earth. She then sternly orders WALL-E to go into the pod. WALL-E then asks EVE if she's coming along, but EVE refuses, stating that she has a directive to fulfill, to which WALL-E responds by exiting the pod, not wanting to leave her. No matter how many times EVE places WALL-E in the pod, WALL-E persistently wants to remain with her. Just then, they hear someone coming in their direction, forcing EVE to shut down the pod. Then they witness GO-4 deposit the plant in the pod, making EVE realize that WALL-E did not steal the plant. WALL-E goes inside the pod to retrieve it, but just as he does so, the pod is launched into space, set to self-destruct. Determined to save WALL-E and the plant, EVE flies out into space and goes after the pod, but the pod explodes, leaving a distraught EVE to think both WALL-E and the plant to be lost. But suddenly, WALL-E flies past her, using a fire extinguisher to as a method of propulsion, and EVE is relieved to see that WALL-E has survived. Catching up with EVE, WALL-E shows her the plant, which has also survived the explosion unharmed. EVE stores the plant into her chest cavity and, grateful that WALL-E has saved the plant, hugs him and spins him around. As a way of thanking him, she gives him a kiss, causing a tiny arc of electricity to pass between them, and then the two go on a flight around the Axiom.
After their "dance," they go back inside. WALL-E decides to take this moment to get EVE to hold his hand, but EVE has no time to do so, still determined to fulfill her directive. Not wanting WALL-E to cause trouble again, she places towels on his head and tells him to stay put, then she goes back to the Captain's quarters via a trash chute that leads up to the quarters. After EVE returns to the Captain, she hands over the plant to him, who then asks her what the Earth's current condition is. When EVE doesn't know how to answer, the Captain sticks a device to EVE's head so that he can see footages of EVE's time on Earth, only to find in shock that the planet is polluted and unable to sustain life, even though one plant has survived. But the Captain still thinks that they should return to Earth anyway to recolonize. EVE sees the scene where WALL-E is showing her the "It Only Takes a Moment" scene from "Hello, Dolly" and begins to realize what WALL-E has been trying to say to her. EVE then discovers through her security camera footage that while she was deactivated, WALL-E had been protecting her from all sorts of danger, and she begins to understand the meaning of love and how much WALL-E truly cares for her. Realizing that WALL-E must be waiting for her down below, EVE decides to go back to him, only to be confronted by AUTO, whom the captain has called. After the Captain and AUTO argue, AUTO calls for GO-4, who snatches the plant away. The Captain tells EVE to arrest GO-4, to which EVE points her gun arm at GO-4 and demands GO-4 to place the plant back in her chest cavity. But GO-4 responds by throwing the plant down in the trash chute. Just as all hopes of returning to Earth seems to be lost, WALL-E appears out of the trash chute with the plant that he has caught while climbing up, to surprise of both EVE and the Captain. However, AUTO retaliates by having GO-4 restrain EVE while shocking WALL-E, deactivating EVE again, and sending both robots and the plant down the trash chute.
After being reactivated, EVE finds herself in the ship's garbage disposal chamber and calls out for WALL-E, but she is then confronted by WALL-As (larger counterparts to WALL-Es), who scoop up tons of garbage, along with EVE, and compress them into cubes. Stuck in a cube of garbage, EVE is stacked with other cubes that slide on a platform leading into an airlock. She then sees WALL-E stuck in a cube next to her. Hearing the ship's computer warning the airlock disposal about to be activated, EVE uses her gun arm to blast herself free from the cube and struggles to pull WALL-E free. At the same time, the airlock doors are closing; however, by chance, M-O (who has been cleaning the dirt tracks and followed them to the trash chute) drops into the garbage chamber, rushes towards them after finally finding WALL-E, and manages to wedge himself between the closing airlock doors just as the exterior hatch open. EVE manages to yank WALL-E out as garbage is flushed out into space and, holding onto WALL-E while fighting against the force of air being sucked into vacuum space, reaches out and manages to grab hold of M-O's roller. The three are saved when the WALL-As take notice and shut the exterior hatch. EVE then examines the extent of WALL-E's damage, discovering that his motherboard has been damaged beyond repair. She flies through the garbage chamber, looking for circuit boards, and returns with some, but WALL-E responds that none of the boards that EVE has found will work. WALL-E shows her the plant and persuades her to fulfill her directive, but EVE has changed her directive to being with him. WALL-E then tells EVE that Earth is where his spare parts are and that she can fix him if they go back to Earth. Realizing what WALL-E means, EVE agrees to fulfill her initial directive to get WALL-E back home. She scoops up WALL-E, and the two robots, with M-O accompanying them, blast their way out of the garbage chamber. Joined by other reject bots, they make their way to the holo-detector on the Lido Deck.
Arriving at the Lido Deck, EVE and WALL-E rush toward the holo-detector (activated by the Captain), but AUTO, seeing them, tilts the Axiom, causing WALL-E to sideswipe the holo-detector and drop the plant. EVE puts WALL-E down as she searches around the Lido Deck for the plant, but it gets lost in a crowd of people who have tumbled to a side of the deck. EVE then sees a train falling out of the rails and sliding towards the crowd, prompting her to hold it up to keep it from crushing them. At the same time, WALL-E is using all his strength to keep the holo-detector open as AUTO tries to close it. EVE, while still holding up the train, can only watch helplessly as WALL-E is crushed underneath the holo-detector. After the Captain shuts down AUTO and rights the Axiom, EVE rushes toward the holo-detector to pry it open and free WALL-E, but it won't budge. She calls to the crowd and the robots for the plant, and when M-O finds it, the plant is passed up to EVE, who then promptly inserts it into the holo-detector, activating the device. WALL-E, crushed and severely damaged, rolls out of the holo-detector, and EVE desperately tries to wake him up, to no avail, as the Axiom makes its hyper-jump to Earth.
After the Axiom returns to earth, she rushes WALL-E back his trailer and repairs him, giving him new wheels, new binocular eyes, and a new chip. After WALL-E is charged up, he appears to be well. EVE tries to get his attention, but WALL-E goes to do what he is programmed to do as if he is an emotionless machine. EVE tries various ways to make WALL-E remember, but nothing happens, as WALL-E sticks with his original directive, scooping up garbage and compressing them into cubes. When all her efforts fail, she becomes heartbroken that her lover is gone forever. She holds WALL-E's hand like what he has wanted, hums "It Only Takes a Moment," and gives him a farewell kiss, causing another arc of electricity. She then turns to leave in sadness, but her hand is still stuck inside his hand. As EVE turns to examine WALL-E, his hands slowly close on her hand, his eyes focus themselves, and he calls out her name, making EVE overjoyed. The kiss has rebooted his memory. EVE and WALL-E share a tender moment, holding hands, staring into each other's eyes, and sharing another kiss with no arc of electricity this time. Then they begin dating and help the humans make earth sustainable and beautiful again.
It is unknown what becomes of them following the events of the film.