Natsu is Natsu... he's someone who cares about his friends more than anything, he's E.N.D but that does'nt make him any less human than anyone else and he's also an amazing fighter who fights for his nakama and nowone else
end or entherious natsu dragneel is the book of end and when ever zeref or somebody punches it. it hurts him its really not suprising heck igneel was always living in natsu body a demon with the strongest durbittly in mind hes E.N.D. hes from the books of zeref he loves and cares for his friends.
E.N.D ETHORIOUS NATSU DRAGNEEL a demon from the book of Zeref, him and Wendy, Sting, Rouge, Gajeel, all the dragon slayers who were taught by dragons are more than 400 years old, the Heartfilia's have been guarding the Eclispe gate for a long time and the time when Layla used it she brought the dragonslayers through, that is the reason why they couldn't go through the enchantment "you have to be 80 years or younger to pass through the enchantment."