In the RigVeda the Asuras are not yet demons. At that time the Asuras and the Devas were both still groups of gods. In fact, many of the figures of the RigVeda are both "asura"s "and" "daeva"s. This is because, at that time, the two words were not yet names of groups. They were just names of characteristics. "Asura" means "life", and so the gods who were called "asura"s were thought to give life. And the "daeva"s were shining. This is the original meaning of the names. In later books they became different. 