How does the mongoose show persistence in "Rikki-Tikki-Tavi"?

In the story “Rikki-Tikki-Tavi,” the mongoose after whom the story is named shows persistence in at least two places.  In both cases, he shows it as he protects “his” family from the cobras that want to kill them. 
In the first instance, Nag (the male cobra) wants to kill the man of the family in the house’s bathroom. The mongoose shows persistence by waiting patiently for Nag to go to sleep. The story says that Rikki-Tikki “stayed still as death” for more than an hour before he struck and tried to kill the snake. Once he bit Nag, he showed persistence again. He held on as Nag whipped his head back and forth, battering him against walls and various other hard things. Rikki-Tikki “was dizzy, aching, and felt shaken to pieces” before the man came and shot Nag with a gun. This shows real persistence.
At the end of the story, the mongoose shows persistence again. He kills all but one of Nagaina’s eggs and brings the last one to distract her and prevent her from killing the young boy of the family. He dances around for a long time, avoiding her strikes. Then, when she grabs the egg and makes off, he chases her down. He knows that he has to kill her and the last egg so that there will be no more snakes to threaten the family. He follows Nagaina into her burrow (a very dangerous thing to do) and kills her. In both of these instances, Rikki-Tikki shows persistence because he refuses to give up until he has done everything he can to protect his people.
http://www.cs.cmu.edu/~mongoose/rtt.html