it explained in the episode how she became a dalek.
She didn’t only appear when the doctor needed her, she lived a life every time. She joined the Alaska to see the universe and crashed into the dalek asylum before she met the doctor, and became a dalek and met him then is all.
EDIT: I mean there’s obviously still more to know with what River said, but yeah.
What that other reply said. She basically assumed all roles in his life that she was ‘needed’. This role could be as short as telling him which tardis to take, or as complex as being captured by the daleks, being turned into one and actually being 1
Ah yeah it makes more sense when you put it like that, I mean the story of that is not shown obviously, but I see how it fits with the overall continuity.
You know, I still don’t think Clara in the Dalek asylum has been properly explained. I understand how she’s appeared in the Doctor’s timeline all those times, because of what happened in this finale episode and whatnot, but how did she become a Dalek?
Either there’s still more to Clara than we know, or we’re gonna pretend that just happened ‘somehow’…