Athelfled, Lady of the Mercians

 Athelfled (more properly Æþelflæd), Lady of the Mercians, was the eldest child of King Alfred the Great of Wessex. We don't know when she was born, but her father became King at the age of 22 in 871 AD, so around then or a few years earlier seems likely. Nor do we know when she married Athelred (Æþelræd), Lord of the Mercians. He blasted onto the stage of history out of nowhere in 883 when he acknowledged Alfed as his overlord (we don't even know if he was a Mercian by birth). They married some time in the 880s.
Athelred stopped functioning politically (why? illness seems most plausible, but there's no direct evidence) at the beginning of the tenth century, as much as a decade before his death in 911. Athelfled took over, ruling as regent till her husband died and then in her own name as the autonomous Lady of the Mercians until her own death in June 918. They had one child, whose date of birth is also unknown. Historians can navigate happily around these shoals of unknowing. A historical novelist has to make choices about such important issues as the age of a major character, and when she becomes a mother. My choices about Athelfled's life have been dictated by the needs of the story, as has the decision to call her 'Fleda', a culturally-feasible shortened version of her name. It was simply not possible to write a story with characters called Athelfled, Athelred and Athelwald, even if I tried to keep them from sharing the stage at the same time.