An experiment of few words, Yang was shown to be fiery, short-tempered and hotheaded before his rehabilitation. He is single-minded and will focus only on what is right in front of him, paying little heed to anything else going on around him. This clearly demonstrates an overconfidence in his own powers, as Yang considers them more than adequate to handle any threat. He is shown to not really care what other people want him to do, and has a tendency to be boastful. However, he would defend his friends and ʻohana loyally, alongside Yin.
Experiment 502 was the 502nd genetic experiment created by Jumba with Hämsterviel's funding. He was designed to spout balls of lava from his back. 502 and the other first 624 experiments were deactivated and smuggled to Earth by Jumba during his mission to capture Experiment 626.
All of the experiment pods were released and scattered across the island of Kauai, with 502's pod landing in a fissure in the ground on a mountain road.
When a stranded man poured water into his jeep's burnt-out engine, the water flowed out into the crack and onto 502's pod, activating him. 502 then erupted to the surface and set out to cause chaos.
While attempting to cross a road in front of a car, the car's owner scolded 502 to get out of the way, causing the angered experiment to destroy the driver's automobile.
502 later entered Kokaua Town and went on a rampage, destroying everything in sight. Stitch jumped onto one of 502's back spouts to try and stop the latter, but 502 simply blasted him off and most likely continued his rampage.
Stitch's incompetence caused a rift between him and Lilo, and each of them insisted that they could catch an experiment without the other. Stitch then joined up with Jumba, and Lilo joined up with Pleakley to find out.
Later, while 502 was scratching himself, he was ambushed and blasted into a net by Gantu. However, 502 was able to escape by simply using his lava to melt through the net.
502 was later chased by Stitch and Jumba through a jungle, but the two failed to catch the former. While continuing to flee his pursuers, Experiments 502 and 501 met for the first time. Jumba erroneously stated that if they both touched, Earth would likely be destroyed. However, they were ambushed and captured in containment orbs by Gantu before they could make physical contact.
When Lilo later tracked 502 down, the latter attacked her with fireballs. However, Lilo was able to block off 502's lava attacks long enough for Stitch to immobilize 502 via anti-heat foam, rendering him defenseless.
501 and 502 were then rehabilitated, named Yin and Yang, and given a one true place using their combined powers to create a whole new island.
Yang reappeared in "Elastico" as one of the audience for Lilo's hula dance.
In "Houdini", Yang was one of the audience for Stitch's bungled magic act.
In "Dupe", Yang was one of the experiments that came to Lilo and Stitch's slumber party wearing pajama pants and bunny slippers. However, he was forced by Pleakley to leave due to his destructive behavior.
In "Angel", Yang was one of the experiments that Angel reverted to evil using her song. Later, Yang and the other depraved experiments attacked Stitch aboard a ship, but Angel turned them back to good before they could finish Stitch off. Working together, the experiments were then able to successfully escape the ship along with Stitch.
Yang reappeared in "Slugger" as part of Lilo's softball team.
In "Ace", when the head of E.G.O. arrived on Earth to decide whether or not Jumba was still evil, Yin and Yang posed as mutant creations as part of a hoax to fool the head of E.G.O.
In the film's opening, Yang can be seen waving hello to Lilo, along with Yin and Cannonball. Yin and Yang were also seen later in the movie as Lilo was making her rounds with Scrump to make sure all the experiments were happy in the one true place they belonged.
Later, the first 624 experiments, including Yang, were rounded up by Leroy and taken to a stadium to be destroyed. However, Lilo, Stitch, Jumba, Pleakley, Reuben and Gantu arrived before the experiments could be destroyed.
Yin and Yang participated in the following battle between the experiments and the Leroy clones by using their combined powers to encase Leroys in rock. Yang also shot balls of lava at Leroys.
However, the Leroys soon gained the upper hand in the battle, but were defeated when Lilo, Stitch, Reuben and several other experiments performed the song "Aloha `Oe", which caused the Leroy army to shut down due to the original Leroy's fail-safe.
- His name is derived from the concept of Yin and Yang; in this case his name stems from the force of Yang, which represents masculinity, fire and heat, fitting his nature.
- Yang's pod color is blue.
- Yang is described by the experiment computer screen as, "Experiment 502. Primary function: Lava shooter."
- Yang appears in the online game Lilo & Stitch: Alien Interception along with Plasmoid, Tank, Dupe, Clyde and Hämsterviel.