Ace's timeline
By several accounts, Ace had a unique timeline which was heavily interfered with on multiple occasions, (PROSE: Interference, At Childhood's End, Sometime Never..., AUDIO: Assassins) leading to it being fractured across multiple possible timelines. (PROSE: At Childhood's End, AUDIO: Signs and Wonders)
Fenric was the initial augmenter of Ace's timeline, positioning her into a Wolf of Fenric. In a process similar to but more intentional than the Eighth Doctor's alterations to Sam Jones's timeline, the Seventh Doctor undid Fenric's manipulations using temporal equations. As these equations were done instinctively, Ace's new destiny didn't go quite as the Doctor expected. (PROSE: Interference)
After abandoning her on Earth and fleeing the Time War, (AUDIO: Soldier Obscura) Irving Braxiatel meddled in Ace's timeline as early as her travels with the Doctor. This meant Narvin was unable to track either of them down. (AUDIO: Assassins)