Derek gives Stiles his jacket.

Stiles has come to the realization that he’s going to need to tell the pack that he’s transgender before they find out on their own. He’s only ever told one person before, and he’s still thankful Scott was a true best friend. He only hopes the others take his news as well.

Sheriff Stilinski and his wife couldn't have children. In her desperation, Mrs. Stilinski found a young Selkie boy and hid his sealskin. Only she knew where it was hidden; when she died, so did that knowledge. Stiles grew to love his human family as his own, even grieving the death of his captor/mom, but the sea still calls to him in Beacon Hills.