Based on what little we know of the Time War, and various interesting fanfics, I have made a few decisions:
- The Neverweres and Meanwhiles were all the people who the Time War erased from history. The Could-HaveBeen King was the first one--the son that Koschei might've had if not for the drumming.
- The Nightmare Child was the Master himself. To the Daleks he probably was a nightmare, and he was driven mad as a child. When he returned on the Last Day the energies forming around him were vast enough that they made him look like a giant eating spaceships.
- The Horde of Travesties were people whose very biology had been twisted by the changes in time, devolved and re-evolved in strange ways. They were, however, time-aware enough to know what had been done to them, that they were in the wrong bodies, and they couldn't cope.
- The Skaro Degradations were obsolete--and often alternate--Daleks used as cannon fodder.
- Temporal weapons tend to be based on the problems involved in having half your body moving at a different rate than the other half. The results are . . . unpleasant.
- The Master died four times, was the last survivor of three different squads, and was feared by both sides by the time he ran away.
- There was a woman that the Master remembers getting her arm caught in a time loop, one that he was desperate to rescue. But other than that one memory of rescuing her, he has no clue who she was--she was grazed by timefire, apparently. Sometimes he has nightmares about her, the friend that he's forgotten. Sometimes he thinks she's right next to him, trying to get his attention. Maybe she is.
- When the War got bad enough, the Master was one of the first people to think of hiding out in the Death Zone. He spent about a subjective year there, mostly killing anyone else who entered so the War wouldn't reach his safe haven. (Eventually the war came anyway; a Dalek time bomb landed right in the middle of the Zone and failed to detonate, leading to squads from both sides trying to retrieve and study it. The Master was so angry about this that he spontaneously invented a remote detonator for the damned bomb and set it off just as the squads arrived. Don't make geniuses angry, kids!)