All throughout the Riverlands plotline, our main characters (Catelyn/LSH, Jaime, Brienne, Sandor Clegane, etc.) have all been after one (or both) of the Stark girls. Since GRRM is such a great writer, he amazingly has characters thinking they are on the trial of one and they are actually missing the trail of the other. In this post I am going to briefly (I will flesh it out more if people like it) theorize on how it could end.

Sansa/Arya and the End of a Major Riverland's Plotline

While the Brotherhood without Banners is killing Freys left and right, its forgotten that since they lost Arya they have been tracking her diligently. The problem was once the Hound's helm was taken by Rorge it threw off their search for him.

That said both Jaime/Brienne have information that could lead Lady Stoneheart/the BwB to Sandor/the Quiet Isle (Podrick may have recognized him).

So I would expect at a minimum this to be discussed in the next Riverlands chapters (Jaime or Brienne) where they were last seen leaving alone together since "the hound has Sansa". Since this new information could put the BWB back on the trail of Arya they head in that direction.

At that point I really can't say what will happen outside of point to a few interesting facts:

If they head to the Quiet Isle to confront Sandor

• Lem Lemoncloak (potentially Richard Lonmouth) is the "new Hound"
• Both Jaime/Lady Stoneheart would recognize him
• The Elder Brother might just give them all the info on Arya possible (after first declining idk)
• Worship of the Lord of Light has grown in the Riverlands

If they just reach his grave and then start asking questions

Arya left the Saltpans aboard the Titan's Daughter, with Brienne glimpsing it upon its return:

Lord Randyll's men still prowled the docks, as thick as the flies had been on the heads of the three Bloody Mummers, but their serjeant knew Brienne by sight and let her pass. The local fisherfolk were tying up for the night and crying the day's catch, but her interest was in the larger ships that plied the stormy waters of the narrow sea. Half a dozen were in port, though one, a galleas called the Titan's Daughter, was casting off her lines to ride out on the evening tide. -AFFC, Brienne V

As I keep mentioning this plotline is great because of the uncertainty around which Stark girl the character is on the trail of/going to meet. So (in my opinion) it gets even better since in this case who would be the Titan's Daughter??..... Sansa (aka Alayne the bastard daughter of Littlefinger, whose house sigil is the head of the Titan of Braavos.

So this either could just be a nice little play on words, or it could somehow flip this Riverlands plotline from a search to Arya to Sansa (not speculating how yet really could be anything from her heading south/west or kidnapping by the Mad Mouse).

As I mentioned this is a bit speculative, but also has some logic. If there is interest I can try and flesh it out more.

TLDR: Killing Lannisters/Freys is a major motivation of Lady Stoneheart, but it seems she and the brotherhood are actively searching for Arya. This could lead to a strange twist for this Riverlands plotline.