User blog comment:FairyRaven/Fairy Tail Chapter 425: Sabertooth X792, Review and Commentary/@comment-76.121.234.236-20150323112525/@comment-125.212.122.57-20150323120103

Natsu knows that Frosch will be killed by Gray around that time. He just added 1 + 1 so maybe now he thinks Gray turned to the dark side that's why he have to bring him back.