Soto is an alien from another planet whose cellular structure is composed of living stone. He originally owned a dog, but the dog was far more intelligent - and cultured - than his master, who in turn was very childish. No longer willing to remain with Soto, who did not appreciate his intelligence and free will, the dog escaped to Earth in an escape pod, but was relentlessly tracked by Soto and his ship.
During his flight, the dog accidentally ran into Beast Boy, who was kidnapped in his stead. Soto lost no time clapping Beast Boy into a collar which would keep him captive no matter what shape he assumed. Excited by Beast Boy's wide range of possible shapes, Soto instantly decided to keep Beast Boy as his new pet and take him back to his home planet, disregarding the latter's protests to the contrary.
In the meantime, the other Titans, who had mistaken the dog for Beast Boy, learned the truth about their quarry, who offered his help in finding Beast Boy. They managed to prevent Soto from taking off, but Soto himself proved to be too strong and resilient even for their combined powers. But then Beast Boy, freed of the collar, appeared on the scene and soundly thrashed Soto, and the collar ended up on Soto's neck instead by his own dog's tongue. When the dog refused to submit to the role of the pet anymore, Soto enthusiastically adopted the role of the pet for himself, and Soto and his new master left the Earth, leaving Beast Boy to reunite with his teammates.
Soto is childish and may be a baby (because of his intelligence). Like normal children he throws tantrums when he doesn't get what he wants. He can cry at times but he is a formidable fighter. Like normal owners he scolds his dog(s) for not doing what he is told. Soto is willing to do what it takes to keep a pet, even by becoming one himself. Soto's feelings are also easily hurt. When Beast Boy wanted to go back to earth Soto started to sob, but Beast Boy didn't want to hurt his feelings (or get shocked). He also broke into tears when Robin cut the trunk of the tree he was using as a club, an act which surprised the Titans.
Powers and abilities
With his stony body structure, Soto possesses formidable strength and resistance to massive amounts of physical damage.
- This character is named after series co-director Alex Soto.
- Soto's head was modeled after the famous Easter Island head statues.
- Soto is one of the two antagonists in the show physically made of stone. The other being the reoccurring character Cinderblock.
- Soto may be an infant or toddler of his species, judging from the decoration of his ship, which resembles a child's playpen, and his spacesuit, which looks like a baby's onesie (complete with a butt flap).
- Though Soto is an antagonist, but he is not a villain; all he wanted was a pet (or company since instead of releasing Beast Boy he keeps him).
- Sometimes, Soto has the ability to literally "Laugh his head off".