In this fanfiction, once Natsu loses his arm, the story progresses in several ways. At first, there's shock and sadness among his friends and the guild. Natsu has to come to terms with his new reality. He starts to train differently, focusing more on his magic control. There could be a sub - plot where an enemy tries to take advantage of his weakened state. But Natsu, with the help of his friends, overcomes these challenges. He may also meet some new characters who have knowledge about arm - restoration magic or something similar. As he embarks on this journey, the story could explore themes of perseverance, friendship, and the power of the human (or in this case, dragon - slayer) spirit.