Lost Prodigy Girl Returns

The alliance leader takes the child because of what her body is worth: refined properly, a girl born with that constitution becomes an immortal elixir. A wandering master intercepts him and carries her up into the mountains instead, and she is raised there on pill cultivation while her family searches the roads and finds nothing. Eight years pass. Molly comes back down the mountain skilled enough that elders defer to her, and walks into a home that is already collapsing. The family's martial academy is being destroyed by enemies who are still circling it. Her relatives recognise her and refuse to say so out loud, reasoning that a girl nobody knows is a girl nobody can use against them. She is turned away at her own gate, and she believes it. She is on her way out of town when the alliance leader arrives at the house himself, which ends the pretence for everyone. Molly stands between him and the family that just disowned her, and afterwards her master sends word that the abduction eight years ago was not the accident she has always been told it was.