Nava is the protagonist of the story and the only character who makes a proposal.
At the beginning of the story, we learn that Nava is a wanted man. There are men looking for him who want to kill him for a crime that he committed many years ago. The crime he committed was the brutal murder of his neighbor. Nava proposes that his son, Justino, should ask these men for mercy on his behalf.
At the end of the story, Nava is confronted by the son of the man he killed. Nava proposes to this man that he should be allowed to live because he has suffered enough already in his life. He says that he has already paid "many times over" for his crime and, therefore, should not be made to pay again.
Both of Nava's proposals are ironic because he is asking for mercy even though he showed no mercy when he murdered his neighbor. This is situational irony because Nava is expecting, or at least hoping for, something to happen that is very different from what actually does happen. Indeed, his requests for mercy are ignored, and he is duly executed for his own, merciless crime.