Maybe the tattoo on Natsu’s hand foreshadows the fact that Natsu’s the one who’d gonna defeat E.N.D.?
If they are two separate entities, then fine. (I think Gray would face E.N.D. first then Natsu? then nakama power lol)
If they are the same person then it’ll be Natsu vs. self? (nakama talk is…
I really have to admit sth: I hate all those theories about Natsu being E.N.D. cause that’s not even reasonable in my opinion. Furthermore, I couldn’t stand it if he is END (what he’s not) just because everyone would be in pain (especially Lucy). I think, I would blackmail Hiro Mashima until I get what I want gehee xD