"I trained enough turkeys who never came true. You're my one last hope so you'll have to do."Many years ago a great teacher oversaw a promising young pupil. It went bad, probably because he turned to evil or ended up showing his true colors, maybe even becoming the Big Bad. As the Master-Apprentice Chain continues there's now a young hero being trained by the elderly Mentor. The Hero might have been Desperately Looking for a Purpose in Life so he feels like he fits somewhere when he hears in back story how his overseer/teacher also trained another some years ago, but that pupil went to The Dark Side and became the antagonist of the story. Now the teacher plans to use his second chance and hopes that this chosen one, who is the current protagonist, can stay good. This is what might come after A Pupil of Mine Until He Turned to Evil.
— Phil, Hercules
- Fatal Fury: In the anime adaptation, Tung Fu Rue was sempai to Jeff Bogard and Geese Howard. However, Geese felt slighted when Tung chose Jeff as his successor and murdered him in retaliation. Years later, Tung takes Terry Bogard as his new pupil, and trains him in order to avenge Jeff's death.
- Jiraiya from Naruto sees teaching the title character as the only thing in his life he ever did right.
- The title character of Kenichi: The Mightiest Disciple is seen like this by his masters. They previously had Isshinsai Ogata as a disciple many years ago. The Elder recognized his sinister intentions right away, but Kensei and Akisame trained him for a while before his true nature because apparent.
- The old wizard Shazam gave an Egyptian Teth-Adam (Mighty Adam) the same powers he later gave Captain Marvel, but Teth-Adam had a Face–Heel Turn so Shazam renamed him Black Adam and sent him 5000 light-years from Earth.
- Luke Skywalker from the Star Wars saga was started down the path of the Jedi by the original Obi-Wan, who in the past taught Luke's father Anakin Skywalker before he turned to The Dark Side and became Darth Vader. Unfortunately for Obi-Wan, he didn't get to try to steer Luke away from the Dark Side before Vader killed him, and so the task fell to Yoda, the old master who had a part in training both Obi-Wan and Anakin.
- In Kung Fu Panda Tai Lung is the first devoted pupil of Master Shifu before the story starts. Now he is the enemy of Po and the Furious Five.
- Hercules is this to Phil in Hercules according to the latter, as he'd trained so many heroes before who "failed" to live up to their names.
- In Harry Potter young Harry is wisely watched over by Dumbledore, who also kept a close watch over Tom Riddle before he became Lord Voldemort.
- This is part of the back story of The Giver: The Receiver of Knowledge who mentors Jonas is revealed to have had another protege in the past, hinted to have been his own biological daughter (in their society, children are assigned to parents other than their birthmothers), who committed suicide out of despair brought on by the knowledge she received from her mentor, and was unpersoned by the Community.
- This could very well be the case with Socrates and Plato, the latter being Socrates' best-known pupil. Socrates was known for having many students, some of which went bad. Perhaps the closest thing to a "Darth Vader" in ancient Greece was Alcibiades, a general who once served Athens but defected to Sparta... and a number of other places (long, confusing story there), but was generally seen as a pupil gone bad, while Plato went on to form an academy of his own to continue Socrates' work, the original Academy, in fact (in a grove sacred to the ancient hero Cadmus).