Swapper

Swapper, A.K.A. Experiment 355, is an illegal genetic experiment created by Jumba Jookiba and a character in the Lilo & Stitch franchise. He is designed to switch people's minds; it is possible for him to swap more than two individuals at once, and he will only switch them back by choice. His one true place is allowing others to see things through the perspective of an individual's mind.

Personality
Because Swapper is two heads on the same body, Swapper is two beings cooperating as one, though their personalities mirror each other: they can be indecisive at times but usually work well together. An example is when Stitch in Lilo's body asked the two-headed cousin to switch their minds back, Swapper, after hesitating, blew a raspberry in response. The two enjoy messing with people by swapping their brains and refuse to switch them back unless threatened. However, Swapper will eventually switch individuals' minds back into their original bodies when both heads choose to do so.

Physical appearance
Swapper is a green lizard-like experiment with two heads on a conjoined body at the rear. Both sides of the body have a set of arms, but only one pair of legs and purple markings extending to each. He has three purple-tipped tendrils on each head.

Powers and abilities
Swapper can emit a green ray from each head's eyes once each head is pointed at one of two individuals. The ray will swap the minds and voices of the targets, as well as vice versa, and the only means of returning to normal is through Swapper choosing to do so. Although he normally uses his power on two people, Swapper isn't limited to this specifically, since he was able to hit four beings at once. He can also scale walls and roll into a wheel-like shape.

Lilo & Stitch: The Series
Experiment 355 was the 355th genetic experiment created by Jumba with Hämsterviel's funding. He was designed to swap any two (or more) individuals' minds. According to Jumba, 355 once swapped the former and his wife for an entire month, which led to a divorce in the end. 355 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.

At an unknown point after this, Experiment 355 was activated and captured by Gantu.

When Gantu was about to send 355 to Hämsterviel, 355 got loose and swapped Gantu and Hämsterviel's minds, allowing 355 to escape.

Hämsterviel in Gantu's body then decided to go AWOL and recapture 355 but refused to have 355 switch their minds back afterward, although Gantu in Hämsterviel's body protested.

Sometime later, Lilo and Stitch encountered 355 in town and managed to capture him in a containment orb, but 355 was able to swap their minds in the process.

After 355, named Swapper, refused to switch Lilo and Stitch's minds back, they took him back to their home, where Jumba covered up Swapper's container with a towel to prevent the latter from using his mind-swapping power on the former.

When Pleakley removed the towel, Swapper switched his and Jumba's minds as well, forcing Lilo's dysfunctional ʻohana to throw a "Lilo's Not Weird" party that she hosted earlier, after Victoria, Mertle and the hula girls showed up.

Later, Gantu with Hämsterviel's mind arrived at the Pelekais' house for Swapper, where a fight ensued during which Swapper switched Lilo, Stitch, Jumba and Pleakley's minds again, though each was in someone else's body.

After Hämsterviel in Gantu's body was defeated, Swapper switched Lilo, Stitch, Jumba and Pleakley's minds back into their original bodies, and was then forced to switch Gantu and Hämsterviel's minds back as well under the threat of being given Pleakley's disgusting cuisine for dinner.

Leroy & Stitch
The first 624 experiments, including Swapper, 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.

Swapper participated in the following battle between the experiments and the Leroy clones, but it is unknown what he did.

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. Swapper joins them for the song by playing the keyboard.

Stitch!
Swapper made an appearance in the Stitch! anime, where he used his powers on Stitch and Hiroman. Until they could find Swapper again, Hiroman needed to figure out how to use Stitch's abilities to take on Heat. After Heat, Gantu and Reuben were defeated, Jumba made a request for Swapper to swap Stitch and Hiroman back into their original bodies, but he instead swapped everyone's bodies again.

Trivia

 * Swapper's ability to is a very common TV trope seen in various fictional media, also known as a Freaky Friday Flip, named after the 1972 novel and its three film adaptations (also produced by Disney).
 * Swapper's pod color is blue.
 * Swapper is described by the experiment computer screen as, "Experiment 355. Primary function: Swaps people's minds."