User blog comment:Derax-Pagani/Chapter 509: Kagura vs. Larcade Review/@comment-1359322-20161107120121/@comment-130.105.140.154-20161107122007

"Why did Mashima even bothered letting Jellal survive past ToH and let OS go free from prison in the 1st place."

This is what we call "Chekhov's Gun".