This study aims at analyzing the structure of narratives about the first battle of the three Iranian heroes Garshasb, Sam and Rostam to define the common structural pattern in them and compare it with the myth of Indra’s fight who was the Indo-Iranian god of war, with Vitra, the evil god of drought. With this purpose, and using a structural analysis of myth, narrative segments of these heroes’ first battles will be defined and their mythemes will be compared. Then, it will be revealed how the structural patterns in these narrative are in consistent with Indra’s first and famous battle. The aforementioned battles take place in parallel with an event that is the young hero/god becomes his father’s successor by removing his authority. Thus, the result of the research suggests that there is an intertwined relationship between the fight of Indo-Iranian hero with dragon, and the elimination of the venerable status of the hero’s father. It seems that these two events are somehow the transformed forms of one another and each is the alternative for the other one. Here, there is one linking element that keeps the two sides of the equation connected like a chain, and it is the weapon of having a father, i.e. the symbol of father`s power to defeat the dragon and consequently denying the father’s authority.