AU, from the end of 3x07 in which certain events don't happen and Brienne ends up as the reluctant guest of the Lannisters in King's Landing. (TV universe only, though some details from the books might sneak their way across)

One night shortly after his arrival in King's Landing Oberyn is approached in the gardens by a stranger, hooded and cloaked. When she asks him to help her die, he takes her back to Dorne instead. Taking her to safety is easy enough; keeping her safe is a different matter.

Sansa burns Winterfell as the Night King approaches. Somehow, her story continues.

Jaime didn’t like the Starks at all. He didn’t like their earnestness and honesty and prudishness, he didn’t like their cold heavy-walled castle, he didn’t like their frozen block of a realm, and he especially didn’t like Robb Stark, who had saved his son’s life and been kind to him and got him to sleep, and what business of his was it to have done any of those things?