Papa Lightning (イナズマ の おやつ さん Inazuma no O Yatsu-san ) is the name given to a wise teacher featured in Metroid EX chapter 4, who walks with a cane. After crash-landing on his home planet Jatsuk, Diesel meets Papa Lightning for the first time since he left the planet due to disagreements over the use of their race's machinery talents. Their race was once renowned for its talent of repairing and making machinery, but stopped doing so when it began to be used as weapons of mass destruction. It was a unanimous clan decision to stop making machines, but Diesel disagreed and left to open up the Junk Quixote.
Papa Lightning and the clan refuse to return to their technological ways even when Blast threatens them with a Bomb, but change their minds when Diesel decides he cannot dismantle the Bomb and instead chooses to craft an offensive weapon out of it. Their efforts pay off, and Blast is killed. Papa Lightning helps the Craftsmen to repair Samus' Gunship, using parts from their own ships, and installs a failsafe in it that Samus uses in the next chapter to escape Rockets' continuous attacks.
Papa Lightning and the craftsmen return in chapter ten to save Joey, Diesel, and the defecting Greed Corps general Knight from an interstellar execution. He explains that they followed the trio in a newly-developed Multidimensional Stealth Warship to ensure Diesel didn't do anything rash. He attaches a Perfect Drill to their cage and sends it back into the galactic ruins so they can rescue Samus while the craftsmen assist the Galactic Federation armada against the Greed Corps.
"Papa" is an honorific title; this character is not actually Diesel's father.