User blog comment:Bunnyllove/If Igneel is king of the fire dragons what would that make Natsu?/@comment-24162515-20131113002530/@comment-7418318-20131113081318

Just because Atlas Flame did, doesn't mean the others (if there are any) will do the same.

Atlas Flame considered Igneel a good friend and Natsu freed him from a mind-controll spell. Surely those two facts also played a big role in how Atlas treated Natsu.