so what if the Gods of Light and Dark weren't just two separate beings? what if they once were One? what if something happened -- someones happened -- and the two halves were ripped apart?
what if the two halves of this previous God finally met again? what if they discovered (and rediscovered) themself as they had been before? what if they discovered what they are now, with and without each other? what if they fell in love?
what if the God of Darkness is dying from the leftover wound of their long-ago severance? Draining and bleeding away until there's nothing left of her, just as the God of Light found her again? what if they can't put the two halves of the former God back together again? what if, with the help of a certain Doctor, they have to figure out how to stabilize and rebuild the God of Darkness, the way the God of Light was by those who took his half so long ago?
what if they run out of time?
(please note that these ideas have like. little to no actual ties to the Doctor Who canon or story. this is 95% just stuff in my head. an alternate universe if you will. this whole thing might entirely clash with the OG storyline of Doctor Who and Lux Imperator and the Pantheon but tbh i don't actually care, i'm enjoying this story idea far too much :3)