Morty first appeared in the couch gag for the episode Mathlete's Feat known as the Rick and Morty Couch Gag. Morty was driving the space cruiser because Rick was presumably teaching him how, and he ended up messing up and crashing through the wall, killing the Simpson family. Morty was struck with fear because of this and because he was the one who killed them, he was the one put in charge of bringing them back. Rick then helps solve the problem by scooping up the remains of the family in a vile and giving it to him along with their family portrait. He tells him to go to another dimension and clone them so that they can come back. He uses the portal gun to open a portal there and sends Morty in while he stays at the house to clean it up. Morty enters a strange dimension with foreign writing and strange kinds of aliens and nervously follows the directions on the address he's given. Morty goes to a store where an alien is working and he gives him the vile and picture. The cashier takes the vile and feeds to to an alien animal and then takes some strange balls of alien goo out from the animal's snout and gives it to a very disgusted Morty. Morty returns to the Simpsons dimension and gives Rick the bag of balls. Rick dumps them all out on the couch and turns of the thermostat which causes them all to mutate and grown into The Simpsons. However, something goes awry when they all end up being mutated, disgusting looking versions of them with Rick's skin and hair. Rick then says that the reason for that is because his DNA got mixed into the vile from cleaning it with his own saliva. He then takes his bag of stolen things and he and Morty get back into the cruiser and fly off, realizing there's nothing else they can really do.
Morty is a young teenage boy. He has short brown hair that's worn straight and neatly combed around his head. Morty's head in round and roughly in the shape of a circle, unlike many other characters in the show with their oval-like heads. He has a yellow shirt and blue pants and white shoes. He speaks in a very forced and nervous voice that constantly cracks due to him going through puberty.
Morty is a young, good-natured, and impressionable boy who can be somewhat easily manipulated. He has been described as 'challenged' and has difficulty in school. He also has a stuttering problem. Despite his lack of intellect, Morty has shown to be a good listener and follows directions well. These traits make him the perfect sidekick to Rick. He is interested in Jessica, a student in his math class.