Board Thread:Lore Discussion/@comment-24420450-20140114023310/@comment-14027812-20140114153515

They're not broken off of Akatosh, they're broken off with Akatosh from the original Time God, AKA. It's not as complicated as I am making it appear, just think at it as all of the dragons being the same, yet with different minds. Another explanation for Alduin's personality is that his intended role was to destroy the world, but he deviated from that path in order to become the world's ruler, as dragons tend to have a certain instinct for dominance.