User blog comment:IamJakuhoRaikoben/Chapter 415: And It Shall Become Your Will To Live, Review./@comment-24546844-20150110204315/@comment-7418318-20150111001046

The things you mentioned about Acnologia and the Dragon Souls reminds me of Eragon, where the main antagonist grew as powerful and lived as long as he did due to harnessing dead Dragons.