User blog comment:Noramehablia/larcade and natsu/@comment-30462872-20170418123755

He was one of Zeref's demons, so is Natsu because part of him is E.N.D, Zeref's greatest and vilest demon. Also, Zeref stated that Larcade was the closest thing he'd ever created that compared to Natsu, so it stands to reason that he is very similar anyway with how he was written.