User blog comment:Bluefox87/Chapter 416 Natsu is E.N.D...WHAT?!?/@comment-76.121.234.236-20150124114938/@comment-25032153-20150124141757

well as he was E.N.D he could have been made to as two separate entities or forms like he is human when he is natsu and he becomes demon natsu or E.N.D some how like doctor jeckel and mister hide though the E.N.D was  sealed some how by Igneel and he saw a fire dragon slayer when he saw the human natsu so he couldnt kill him as they are one and the same person.