Sorine Jurard is an NPC in Skyrim: Dawnguard
She is a Breton Tinker. She is also an archery Trainer.
You have to recruit her to join the Dawnguards  during the quest A New Order
Sorine agrees to help you if you get her a Dwemer Gyro that was stolen from her by some mudcrabs. Once you do, she agrees to hear Isran out.