Aria is an alien life force. She has the ability to take over someone's body and make them do as she wishes.
Aria had taken over Wolverine's body, and caused him to wreak havoc in New York City, leading to the involvement of several Avengers and New Warriors. Out of his control, Wolverine had injured both allies and friends.
Later, Aria reveals to Wolverine that she was testing him to see if he was an adequate vessel. She then transports him to her alien nation, Prison World.