I am trying to find the title of a short story published around 2009, in which a boy travels back in time and has to murder his own grandfather in order to erase his own identity and become a member of a secret group that protects the human race through time.
The story opens with the paragraphs:
This will never happen:
You will flex your fingers as you stare at the back of the youth you are going to kill, father to the man who will never now become your grandfather; and as you trail him home through the snowy night, you'll pray for your soul, alone in the darkness.
The secret group is called the Stasis, and their mission is to preserve human life in the universe for as long as possible by transplanting humans from different eras every time they go extinct. They act to restrict humanity to Earth, and perform cosmic engineering to keep Earth habitable as the Sun heats up, and later as Andromeda collides with the Milky Way.
The protagonist is called Pierce, and the story follows him as he is inducted into the Stasis and goes through training and some early missions and eventually...
rebels against the Stasis, spreading human colonies across the universe.