Xolotl, twin brother to the god Quetzalcóatl, did not want to be sacrificed, so he ran, hiding in various places on Earth until he came to Lake Xochimiclo, where he transformed himself into an axolotl.
In some versions of the legend, he is captured and killed, while in others, he was made to live out his life as a “monster” (in other words, the Axolotl).