I think the key here is that Olenna Tyrell is the real lord of their house and sees Margaey as her successor. She every bit as much Olenna's pupil as Sansa is Little Finger's and Bran is Bryden River's, I don't know how much she currently know, but it seems likely that Olenna would reveal more and more to her has time goes on.
Hey folks, I'm running a small Mastodon server of Twitteros refugees @3eyedcrow , I just started following this community from that instance here, so your post should start pooping up in our federated feed, so hopefully you will start seeing comments from some of our folk. Hopefully, the synergy helps us all out.
I makes more sense if Bran is on the Isle of Faces as a ceremonial king, which would give it the whole severed head Mabinogion vibe.
