Everyone has a story to tell. For The Hero it is their adventures in defeating the bad guys. They likely spent years training themselves in a particular set of knowledge and skills and so if they die all of that valuable information goes to waste. So, often when they get older, they may find someone young and impulsive but filled with a great deal of potential. So they make the step towards finding a protege, possibly even Passing the Torch as they wish to retire. Evidently this likely happens to all Mentor Archetype characters in some fashion, but examples should be ones we actually see happen. Compare Hero of Another Story.
- Examined in an interesting way in the Men in Black movies. The big reveal of the first movie was that Agent K wasn't looking to train a new partner, but was instead training Agent J to replace him. Thus in the second movie J was shuffled off to be the senior agent and known for neuralizing junior agents who failed to meet his standards.
- One element brought up in Star Wars was that Obi-Wan went from apprentice to Jedi Knight to having his own apprentice all in the same day. That apprentice eventually turned to the dark side and became Darth Vader. He later lamented that he was unprepared to be a teacher and regretted his brashness. With the original trilogy we only get this mentioned in passing but with the prequels we see how it actually happens.
- A major aspect of Scrubs is the fact that the characters learn a lot about themselves and how to become effective doctors, thus in the later seasons we see them rely less on the senior staff and instead become senior staff themselves. It is made most prominent in the last two seasons, where J.D. finds himself stepping into the same position his mentor did for him. This was hinted at as early as the first season when J.D. had to be a big brother mentor to a nervous med student and imitated the mannerisms of Dr. Cox.
Hello, Unknown Troper. You'll need to get known to lend a hand here.