521 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. Against statistically unlikely (but not impossible) odds, several experiment pods landed in one location: Mrs. Hasagawa's yard, 521's pod being one of them.
At an unknown point, Mrs. Hasagawa mistook 521's pod for an apricot and washed it, activating the experiment. However, as 521 was not a very evil or destructive experiment, he was able to live a peaceful life with her, due to the latter seeing the former as a mere stray cat who needed a home, though he instinctively wrapped the end of her table.
When Lilo and Stitch discovered that Mrs. Hasagawa, kept several experiments as pets, they thought they were a danger to her and, along with Jumba and Pleakley, decided to capture them all. Eventually, 521 completely mummified both Jumba and Pleakley in his wrapping, though due to having been previously affected by Experiment 358, they were too polite to protest against it. Lilo took 521 off of Pleakley and put him in a container. After freeing the one-eyed alien, she used the wrapping as a makeshift lasso to save Mrs. Hasagawa when she was blown into the air by Experiment 533.
521 and the other experiments were about to be taken away, but were returned to Mrs. Hasagawa when Lilo and Stitch saw how much she cared for them. 521 was then named Wrapper.
The first 624 experiments, including Wrapper, 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.
Wrapper participated in the following battle between the experiments and the Leroy clones.
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 ʻOe", which caused the Leroy army to shut down due to the original Leroy's fail-safe.
Wrapper made an appearance in the Stitch! anime where Hämsterviel modified him to trap people by wrapping them up in boxes like presents. He does so by spitting a box out of his mouth that traps his victim, then uses the red tape on his tail to tie a bow around the box. He later appeared in the special Stitch and the Planet of Sand, where his roll of tape appears to be back to its usual color.
- In Lilo & Stitch: The Series, the color of Wrapper's tape is white. However, in the Stitch! anime, the color of his tape becomes red, most likely due to being modified.
- Wrapper was activated off-screen.
- Wrapper is one of the few experiments to not appear in the group photo at the end of Leroy & Stitch.