A/N: SPOILERS, this takes place shortly after the movie, once the robots are on Earth.
M-O paused to take in the new atmosphere around him. An orange haze hung above the trash skyscrapers and miles of litter. The piled mass of excess consumerism didn't have any effect on him; that wasn't his concern. His internal scanner was searching for something much more important.
The numbers quickly climbed to one hundred. "FOREIGN CONTAMINANT," a monotone voice blared.
A little red siren emerged from the top of his head. He ignored its flashing as he continued to scan the area around him. The ground, one hundred percent — the trash piles, one hundred percent — even the particles that hung in the muggy air, one hundred percent. Everything, "FOREIGN CONTAMINANT."
The little robot had never been off the Axiom. His scanner was programmed to search and obliterate every germ foreign to the ship. This included everything on Earth.
M-O shrieked at his discovery. "Whoa, whoa!" he beeped. This would be a monstrous task. He'd have to clean the entire Earth, or his scanner would eternally flash those least favorite words of his, "FOREIGN CONTAMINANT."
The phrase replayed repeatedly as he frantically began scrubbing the dirt below him. The scanner was going haywire, constantly finding contaminant at every inch. M-O grunted as he darted around, rubbing everything he possibly could with his cleaning tool.
The ground crunched softly as WALL-E rolled up beside the smaller robot. His eyes moved forward, trying to get a better look at what M-O was doing.
"Ohh?" WALL-E chirped curiously.
M-O didn't notice him roll up. He was still too consumed with his microbe-induced panic attack.
WALL-E tilted his head. "Mo?"
Still no response. M-O continued dashing around and hopping about, scrubbing furiously at anything he found.
WALL-E wheeled himself in front of M-O's path. His eyes on the dirt below, M-O bumped right into the little trash compacter.
M-O beeped angrily at WALL-E for obstructing his way. He brandished his cleaning tool, whirring loudly, in WALL-E's face. To him, there was no time for interruptions.
WALL-E didn't move, so M-O huffed, turned himself, and attempted to go around. WALL-E moved sideways to the left, causing the little robot to bump into him once more.
M-O made a noise reminiscent of an electronic growl and moved right, trying to go around the other side. WALL-E rolled to the right and they crashed together for a third time.
Another harsh beep from M-O later, WALL-E was becoming confused at why the tiny cleaner was so irritable. He chirped inquisitively at him.
M-O glared back, wondering how WALL-E could not understand. They were surrounded by potentially dangerous microorganisms — was he the only one concerned with that? After a sigh, he held up his cleaning brush. Once WALL-E got a good look, he gestured with it to the dirt below. He let it buzz loudly for effect. With WALL-E still curiously watching him, M-O again held up his cleaning tool, then pointed with it to a cube of trash. He faked the motion of scrubbing, trying to show WALL-E his intentions. Once through with his pantomime, he turned back to WALL-E and beeped to ask if he understood.
But WALL-E didn't have time to respond. A white blur zoomed between the two, startling them both. The figure abruptly U-turned, and stopped to face WALL-E.
"Oh?" WALL-E was perplexed by EVE's anxious expression.
EVE pointed back to the direction she'd come from. Fast approaching were the slew of defective robots, all beeping and acting haywire. WALL-E bounced happily and clapped; he liked the defects.
"WALL-E!" EVE said sternly.
He slowly stopped cheering as she glared down at him.
It wasn't that EVE didn't like the defected robots — it was that she could only handle them in small doses. It didn't take long for them to begin annoying her. And they were even worse without WALL-E.
EVE and WALL-E's interactions allowed the others enough time to catch up. They slid to a stop, knocking up dust. M-O's siren started to flash at an increased pace.
The malfunctioning umbrella didn't help; it repeatedly opened and closed itself, sending more dirt flying. EVE and WALL-E shielded themselves with their arms and briefly closed their eyes. But M-O simply squealed in anger. How dare that umbrella turn up even more filth, he thought.
The vacuum robot noticed the mess and decided he could help. He forgot, of course, about his defect and sneezed during his attempt. More dust was spread over the others.
M-O fumed, hastily shaking off the dirt. He let out numerous angry beeps at the vacuum's direction.
A pink, hovering robot felt sympathy for M-O. Surely a quick makeover would calm his frenzied nerves, she thought. So she planted a powder-puff squarely on his face, and held up a mirror for him to see. "You look stunning! That is so your color."
"WAHH!" M-O screeched at the sight. He raised his cleaning tool and quickly wiped the makeup off.
From the looks on their faces, WALL-E could tell that neither EVE nor M-O was very pleased at the moment with the defects. But he didn't mind them, so he gladly decided to entertain them for a while. Just so EVE could have some quiet and M-O could continue his grueling work.
WALL-E waved his arms excitedly. He called to the defected robots, encouraging them to follow. When they turned their attention to him, WALL-E sped off. He taunted them to catch him in a game of chase. They happily joined in, speeding off behind him.
Soon EVE and M-O were the only two left. The little cleaning robot looked up to EVE, looming above him. Naturally his scanner ran over her. But he didn't think this would be a problem — EVE was something he expected to be clean. So he was surprised when he heard the dreaded words, "FOREIGN CONTAMINANT."
His eyes widened. That couldn't be right. He just cleaned her a short time ago on the Axiom after her trip to Earth. Did she really get filthy so fast? Was Earth really that dirty of an atmosphere? How could he live in such a disgusting, germ-ridden environment?
EVE narrowed her eyes down at him when the scanner proclaimed her as contaminated. She wasn't actually concerned with the diagnosis — she knew she didn't carry anything dangerous — but with M-O's dilemma. She continued to watch and think this over as M-O returned to his frantic scrubbing of everything in sight.
Did he really expect to clean every inch of the Earth?
He had to accept that Earth wasn't foreign — they weren't on the Axiom anymore.
"M-O," she called, floating up to him.
At first he didn't acknowledge her; he was still too consumed with his work. EVE had to shoot a crater in his path with her laser arm to get him to pause. He glanced back at her with a half-curious, half-annoyed look.
EVE approached him from above. She lowered herself down until she was just inches from the ground. M-O was facing the other direction when she pried off the back of him and reached her hand in.
M-O felt his panel move in a way it wasn't supposed to and yelped. He also felt the touch of a few buttons, and then a sudden eerie feeling.
Eve closed the white piece shut. Outwardly, he appeared the same. But something was different. He no longer had the urge to scour everything around him. His scanner had finally quieted.
M-O looked up, asking with his eyes how she did it.
"Earth," she said simply, pointing down. "Not foreign."
She flew off, content in having helped him.
M-O was designed to obliterate microbes — it was his name, his identity. EVE had reprogrammed him to not recognize Earth as foreign contaminant anymore. Because Earth was their home now, and nothing foreign any longer.
He sighed blissfully as he scanned the horizon. Not with his scanner, but simply his eyes. He was happy to be freed of his never-ending task.
Though he was slightly irked that now that his job was chiefly eliminated, he too was one of the defected robots.