His curse is one of conditional mortality, with the desired outcome contingent on her service. When I release her, she will take her place at his side, and travel through time to carry out his orders.
While I am his weapon of subtlety and precision, the Handmaid is strictly an apparatus of terror and suffering. We have both paved the road to his arrival, I in my way and she in hers. She would be present during every watershed moment in her civilization's development. Her recurrance in history would earn her the reputation of a demoness, more feared than even her master, a man though dreadful rarely makes himself seen. She stirred up class warfare and intensified bigotry in whatever era she haunted. She made sure the descendents would enter a world which prepared them well for the game, and took measures to see that they would play as they did.
But once they entered and their world was in ashes, her work was nearly complete. Now, six centuries later, she would be given one last order to follow before her curse was lifted.