1/2
A zap to Archer’s brain from an Expanse anomaly leaves him unable to form short term memory. As such he’s out of commission and can not save Earth. Survivors become a BSG-like group of refugees on Ceti Alpha V.
Future-Phlox, however, figures out that killing the parasites in Archer’s head will alter the timeline, or something – it kinda makes sense when you see it.
The core of the story, though, is of T’Pol becoming caretaker (and lover) to Archer in this future timeline.