Duty of the Living by Jilly James is a Teen Wolf story with a slight Derek Hale/Stiles Stilinski pairing. It's getting there, and it's important, but it's not the main focus of the story. The main focus is on Stiles and his awakening to his destiny.
Author's summary: Stiles leaves Beacon Hills after the events with the kanima. It was supposed to be for a summer, giving him time to get some perspective, but perspective means that Stiles isn’t interested in going back. Not until he’s forced to.
(I finally got off my Avengers kick and fell headfirst into Teen Wolf, which I've avoided for the past decade. I blame Jilly James.)