When you arrive in Natlan in Genshin Impact, you'll eventually come across a Saurian who'll become your companion. Later on, you'll find that the creature is "sick" and needs to be cured at the volcano, which will lead you to complete some quests with the Tepetlisaur. Other than for their health, your companion will also have a series of quests to nurture their growth as a young Saurian.