Theory:

    The stranger strode up to Ranji, who still sat on the rock and, planting his broad feet firmly on the sand, said (as though this would settle the matter once and for all), “Don’t you know I am a Warrior? I do not take replies from villagers like you!”
 
    “So you like to fight with villagers?” said Ranji. “Well, I am not a villager. I am a Fighter!”
 
    “I am a Warrior!”

    “I am a Fighter!”

    They had reached an impasse. One had said he was a Warrior, the other had proclaimed himself a Fighter. There was little else that could be said.
Explanation:
 
The strange boy stepped towards Ranji, who was still resting on the rock. He thumped his broad feet on the ground as he approached Ranji, giving him the impression of a tough boy.
 
Then, the strange boy stated that he was a Warrior. The reason behind the statement was that the strange boy thought that Ranji would run away from his place as soon as he saw his rugged appearance and realised he was a Warrior. Later the strange boy stated that he would not respond to the villagers like Ranji. He said that because he considered himself to be a strong person.
 
Later in response to the strange boy's unfriendly and rude remark, Ranji asked him whether he liked to fight with the villagers. In addition to his previous question, he added that he was not a villager but a fighter instead.
 
Furthermore, Ranji and the other youngster began to praise themselves as "Fighter" and "Warrior". They both found themselves in a situation where progress was impossible because they did not agree with each other. The reason behind the statement was that Ranji and the other boy seemed to be praising themselves rather than ending their argument. Both of them believed they were superior to others. As a result, they continued to indicate that one was a Fighter and the other a Warrior. Beyond the words "Warrior" and "Fighter," they had nothing further to say.
 
Meanings of the difficult words:
 
S.No
Words
Meanings
1
Strode Walk with long, decisive steps in a specified direction
2
WarriorA person who has experience and skill in fighting
3
FighterA person who does not easily admit defeat in spite of difficulties or opposition
4
ImpasseA situation in which progress is impossible, especially because the people involved cannot agree
Reference:
National Council of Educational Research and Training (2008). It so happened. The Fight- Ruskin Bond (pp. 45-54). Published at the Publication Division by the Secretary, National Council of Educational Research and Training, Sri Aurobindo Marg, New Delhi.