Danna was an old tutor at the Time Lord Academy. She was the finest military strategist in Gallifrey's history, and taught Irving Braxiatel when he was younger. She was placed on the research station near the Obscura by Braxiatel to study the Daleks who were trying to understand the Obscura, but also to hide her away, as her abilities made her a dangerous weapon in Braxiatel's eyes. Over time though, she grew older and older, and withered, noting she could, "no longer shoot straight."
She met Ace when Braxiatel came to visit her, and told Ace that she wanted to see Earth after she left the Obscura. Braxiatel discovered that her abilities had dulled, and executed her. Danna later haunted Braxiatel as he made his final plan. (AUDIO: Soldier Obscura)