Ace's timeline

By several accounts, the Seventh Doctor's companion 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)

Known meddling

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)

Ace and the Doctor visited the last resting place of the Wraiths, interdimensional beings that existed in multiple timelines simultaneously, and the home of the Astingir, where unbeknown to her, the Doctor planned to check on the Quantum Anvil - a temporal possibility engine created by the Astingir in their war with the Wraiths which shattered the time streams of the latter into infinite potential outcomes leaving them intangible. He hoped Ace would Ace made contact with the Anvil, enabling her to act as an emissary with the Wraiths. After being grabbed by the Wraiths when she stood too close to their containment, Ace made contact with the Anvil which imbued her with the ability to commune with the Wraiths, but she also saw her life splinter into different outcomes, seeing multiple different possible timelines of her future. (PROSE: At Childhood's End)

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)

Outcomes

Ace's contact with a Quantum Anvil showed her multiple future outcomes of her travels with the Doctor. These included:

• Living on Gallifrey, (PROSE: At Childhood's End) where she trained at the Time Lord Academy and worked for the Celestial Intervention Agency, serving during the beginning of the Last Great Time War. (AUDIO: The Lights of Skaro, Dominion, Intervention Earth, Enemy Lines, Soldier Obscura)
• Travelling in the TARDIS with a dark haired woman. (PROSE: At Childhood's End)
• Fighting Daleks, (PROSE: At Childhood's End) whilst serving with Spacefleet for three years in the 26th century. (PROSE: Deceit)
• Living with an ancestor of Sorin, (PROSE: At Childhood's End) Nikolai Sorin. (PROSE: The Curse of Fenric, Set Piece)
• Dying in a Nitro-9 explosion, (PROSE: At Childhood's End) which she caused to destroy the Lobri. (COMIC: Ground Zero)
• Growing old in the Doctor's company. (PROSE: At Childhood's End)

By one account, shortly after her exposure to the Quantum Anvil Ace declared she was leaving the Doctor. After returning to Earth, she founded A Charitable Earth and years later encountered the Thirteenth Doctor. (PROSE: At Childhood's End)