During the first episode of Game of Thrones, all the Stark children were given a direwolf as a gift from their father, Ned Stark. Unfortunately, over the course of the seasons all but two of the direwolves have died. Jon Snow's direwolf, Ghost, has remained by his side throughout his time at the wall and now back at Winterfell. However, Arya's direwolf, Nymeria, hasn't been seen since Arya sent her away in Season 1 to save her life after she bit Joffrey. However, now it appears Arya and Nymeria will reunite but will Nymeria recognize Arya on Game of Thrones?
It's been six years since Arya and Nymeria last saw each other and that's a long time to be apart. Though direwolves have a strong sense of smell, it seems unlikely Nymeria will remember Arya after all this time. Still, the direwolves have always had a close connection with the Stark children. The direwolf is the Stark's symbol after all. Maybe the connection between Arya and Nymeria will be strong enough that Nymeria will recognize her previous owner.
However, while fans would love a reunion between Arya and Nymeria, that may not have been Nymeria in the preview for the next episode. The wolf in the preview looked a bit different than Nymeria, but it has been six years so that could explain the change in her appearance.
Alternatively, if that wasn't Nymeria in the preview it could be another wolf that is in Nymeria's army. Based on the books, it is suspected that Nymeria has gathered together an army of wolves in the Riverlands. Possibly, it's one of these wolves that first discovers Arya and leads her to Nymeria.
Additionally, in the novels, it was Nymeria that saved Arya's mother, Catelyn Stark, after the Red Wedding, allowing her to become Lady Stoneheart. Since Lady Stoneheart won't be a part of the show and Arya has now gotten her revenge for the Red Wedding, it's believed Arya is taking on parts of Lady Stoneheart's story.
Therefore, it'd make sense that Nymeria comes to Arya's aid while she's in the Riverlands, where Nymeria resides with her army and where she rescued Catelyn. So whether or not the wolf in the preview is Nymeria or if Nymeria jumps in to save Arya, it definitely seems like fans may finally get to see the return of the long lost Nymeria.
Once the pair are reunited, it'll be interesting to see what Arya does next. It'll be difficult for her to sneak around King's Landing with a direwolf by her side. Will she choose to leave Nymeria behind again or decide on a new plan to cross Cersei off her list? Viewers will just have to keep watching to find out.