Alduin - Personality

Arrogant
I don't think I've said this enough. He views himself high above humans and dragons so much so that he views himself as the ruler of the world. Dragon language is his choice of conversing with you. Why? You're a lesser being that is also a dragonborn so you don't need him your language. Also because he views all other races like dirt and uses them as slaves. What a charmer.

Proud
Why would he be proud? Well for one thing, he views himself as the first-born of Akatosh, a huge diety known throughout the land of Skyrim that was the creator. In fact, he used to be considered the greatest creation of the deity but that wasn't enough. Nope, he wanted more and wanted to conquer Mundus for himself and his dragon kin. However, this behavior caused one of his siblings, Paarthurnax, to go "Hell no, you're crazy" and gathered other dragons, rebelled, and got help from the humans.

Destructive
He lives up to his name since he creates chaos and delivers destruction upon the world. Some fire there, squash and swipe some lesser beings there, and never ever eat one. Doesn't help that this guy has a lot of resistance and has quite the magic arsenal to make us miserable. Nothing makes him have more fun I bet other than seeing the lesser beings as slaves and ruling over them.