According to Aztec mythology, Xolotl was a deity closely associated with Quetzalcoatl, a prominent god in the Aztec pantheon. He was believed to be Quetzalcoatl's twin brother.

In contrast to his twin brother Quetzalcoatl, Xolotl is often associated with negative traits, as reflected in his physical appearance and other representations in Aztec mythology. Despite this, he remains a significant figure in Aztec stories and myths.
Fire And Lightning, Dogs And Deformity

The Aztecs worshiped Xolotl as the god of lightning and fire, as well as being associated with dogs, twins, deformities, disease, and disaster. These associations can be seen in the way Xolotl is portrayed in Aztec art, such as being depicted with the head of a dog, and in the stories where he appears.
Additionally, the term "xolotl" in the Aztec language Nahuatl also means "dog". However, it's important to note that dogs were not highly regarded by the Aztecs, as they were considered dirty animals. As a result, Xolotl's association with dogs may not be entirely positive.
A Sickly God

Xolotl's association with illness is reflected in his emaciated, skeletal appearance and his backward feet and empty eye sockets. According to Aztec folklore, Xolotl's empty eye holes were the result of his excessive crying during a ritual in which the gods sacrificed themselves to create humans, in which Xolotl did not participate.
Role In The Creation Story
In Aztec mythology, when the gods created the Fifth Sun, they discovered that it did not move. To solve this problem, they decided to sacrifice themselves to set the Sun in motion. Xolotl was chosen as the executioner, and he killed the gods one by one. In some versions of the story, Xolotl also sacrifices himself at the end, as was required by the ritual.
In certain versions of Aztec mythology, Xolotl is portrayed as a trickster, who attempts to escape the sacrifice by transforming into different forms such as a young maize plant (xolotl), an agave (mexolotl), and a salamander (axolotl). However, in the end, Xolotl is unable to evade his fate and is killed by the deity Ehecatl-Quetzalcoatl.
Xolotl And Quetzacoatl

Despite the Aztecs viewing twins as a type of deformity, Xolotl's twin, Quetzalcoatl, was highly revered as one of the most powerful deities. The two brothers appear together in multiple stories in Aztec mythology. The primordial earth goddess Coatlicue, meaning "skirt of snakes," is believed to have given birth to Xolotl and Quetzalcoatl.
In one version of a popular Aztec story about the origin of mankind, Quetzalcoatl and Xolotl journey to Mictlan (the Aztec underworld) to retrieve the bones of the dead, allowing for the creation of humans. Additionally, Xolotl is also credited with bringing fire from the underworld for the use of humans.
In Aztec cosmology, Xolotl and Quetzalcoatl were considered twin aspects of Venus, with Xolotl representing the evening star and Quetzalcoatl the morning star. Xolotl was also believed to play a crucial role in guiding and protecting the Sun during its dangerous journey through the underworld, as the evening star.
It's possible that this role as a guide may also have led the Aztecs to consider Xolotl as a psychopomp, a figure who escorts the souls of the recently deceased on their journey to the underworld.
In summary, Xolotl was not one of the most positively viewed Aztec gods, given his associations with negative traits and concepts. However, his significance in Aztec mythology cannot be denied, as he played a crucial role in guiding the Sun on its journey through the underworld and escorting the souls of the deceased to their final resting place.