Harpy is the leader of the Twisted Hairs and is unwittingly playing a part in Reese's attempts to create a New Eden; he was the cloaked Cipher that tipped Harpy off about the Brotherhood of Steel base of operations in the Alamo.
If the player character sided with Shale in Austin they will be sent to aid the Twisted Hairs in their raid on the Brotherhood compound. Harpy will brief the player character on the situation and charge them with taking out Paladin Haig, commander of the Brotherhood forces. Once the deed is done Harpy will give the player character a good weapon.
If the player character sided with Keats in Austin they will be sent to help fend off the Twisted Hairs raid on the Brotherhood compound. Paladin Haig will charge the player character with taking out Harpy.