Resources:NARUTO: THE WHORL WITHIN THE SPIRAL, Naruto EP 126, Kakashi and Obito chapters, and the many Minato appearances and references.

Minato Flaws

1. Being too slow to save
2. Being too busy to help the ones in need for the sake of his village or cares about
3. Guilt of Failure

Minato Namikaze personality

1.Likes strong people

2.Shrewd by Tsunade and Jiraiya

3.Caring for his comrades

4.Man who puts his village above everything else

I believe Minato Namikaze learned the Flying Raijin from Jiraiya and a rival who died. This is a fan theory about how and why Minato learned the Flying Thunder God. Throughout his appearance and the people who knew him, these 6 things are made clear. It shapes who he is as a character and what is shown to us in the series.

Minato throughout the story is shown and said to be a once in a generation talent. He scored the highest ever in the Chunin Exams and mastered high level ninjutsu.During the time of the One Shot, he already perfected the Flying Thunder God. This means he possibly learned it during his time as a genin or after he became chunin.Although a prodigy it must have taken him quite a while to learn or even master it.

The reason he is able to learn was because by the results he demonstrated. Jiraiya by then should trust him more with higher level jutsu. He wants to teach him some high level techniques, but wants to find those that suit him well. They train together until a rival of Minato appears. They are possibly on close terms, but not too close because Minato already has people. He was also shown in the one shot to be a popular guy, so I am sure many people would want to meet him.

He asks him what he wants and this rival says he wants to fight Minato. This rival was potentially jealous of the strength and skill Minato had. Many rivals in the series respect or envy the strength of those better than them. Shisui and Itachi, Might Guy and Kakashi, Sasuke and Naruto, Madara and Hashirama, and a few others. It also helps them become stronger shinobi.

Minato accepts this challenge because the rival also has some strength. He also has speed to his advantage as well. Jiraiya potentially oversees this and the two fight in the training grounds. Minato almost wins, but the rival attempts to use the Flying Raijin. It is a new skill but one he has learned. This impresses both Minato and Jiraiya by asking him questions about it.

He tells him that he found out by having an affinity for speed. He also tells them it took him a while to learn the technique and he is not as good at it. Minato is impressed by it and asks to learn the jutsu. They do and the two speed rivals get together on learning the technique. Although this rival learns it, Minato is the only one to have perfected this jutsu.

Minato and the rival wanted to fight one last time to see which one has the better technique. They want to but both Team 6 and the rivals team are called to the battle. This could have been a regular deadly mission or a mission during the Second great ninja war. They fought and use their new techniques during battle. It was during this mission that the rival saves everyone including Minato, but dies during this one last use of the Flying Thunder God. The enemy finishes the rival and takes a while to reach Team 6 and the rivals team.

This death would also affect Minato and harden him on using this technique. Minato would use this technique to the remaining enemy soldiers by himself. Everyone mourns the death of Minato’s only rival. Minato himself promised to use this technique to never be slow again. However, this would potentially set a precedent of his great flaw in himself. Something that Obito would grill him on. Being too slow or too busy to save the people he cares about.

He would fail with Obito, Rin, and his family. Minato would always vow to never be too slow again.He would use this gift to protect people and try to be on time. People grill him for being late which fit into his overall theme.