- Er, pardon me, but I believe we might be able to help one another.
- ―Soto's Dog[src]
Soto's Dog was originally the pet of Soto, an alien from another planet whose cellular structure is composed of living stone. However, the dog was far more intelligent - and cultured - than his master, who in turn was very childlish. 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. While Soto became more and more enamoured with his new 'pet', the other Titans chased after the Dog, thinking mistakenly that it was Beast Boy who was somehow trapped in his current shape. It was after a long, arduous chase through the entire city - just because the Dog was enjoying his new-found freedom and also displayed an obnoxious attraction to Raven, much to the latter's disgust - that they finally got to notice that the Dog couldn't be Beast Boy after all. They devised a trap and caught the Dog with it, but as they pondered how to use it to track down Beast Boy, the Dog demonstrated his true intelligence, and proceeded to strike a deal: In return for his freedom, he would lead the Titans to Beast Boy and Soto.
With the Dog's help, the Titans managed just in time to arrive and 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 for himself, and Soto and his new master left the Earth, leaving Beast Boy to reunite with his teammates.
Powers and abilities
Soto's Dog is an invertebrate shape-shifter who can reshape his body and elongate his tongue at will. In addition, he is not only highly intelligent, educated, and cultured, but also capable of human speech.