as the other comment says, asura/deva were not allways hero/villain split.

King Bali is the perfect example. Bali was called an asura, but he never did anything wrong. He waged wars with devas, and even when devas pleaded vishnu for defeating him, Vishnu recognized his virtues and agreed to push him to paatala (below earth) using trick instead of killing him.

King Prahlad is also another example, he is born to an asura father, but is worshipped as deva. His cousins/sons were again be treated as asuras.

Deva/Asura is calibrated to the speaker. as BBC once said, one man's hero is other man's villain.