User blog comment:- Darkchylde/Acnologia's Element?/@comment-173.87.12.242-20141211055642/@comment-4829046-20141211082236

Morality doesn't really matter in cases where one becomes a beast. He may have been all righteous at a time, but then he let all that power go to his head and now he is a very big threat. And I supposed it depends. You are suggesting he was either misguided or in the role of an anti-hero, which could be the case, but at present, that doesn't seem to fly. All he seems to care about now is his own survival.

You should read the manga though. It is far better than the new anime plus the anime won't get to the interesting point about Acnologia for another year or two.