User blog comment:St0mX/ Natsu & Dragon slayers aging theory discussion v2/@comment-106.208.122.78-20150831090533

I had a thought that when natsu was revived by zeref he turned into a demon(from his original body to a demon form) and after his fight with igneel, zeref sealed his powers in the book of end and he came back to his original body and since he was a demon all this time his original,revived body had not aged at all and he was found by makarov a few years later.

This may be a long shot but I think this could be a theory