Well, his name is Rahkeid Dragneel so we know that he's related to Natsu and Zeref. My theory is that he might be their brother or their father.
posted over a year ago
I dont think he is their father because Zeref s family died and he created end with body of natsu but if he had revive his father too he would be older and 3rd brother doesnt seems likely to me either but he could be