Two Predictions about AKOTSK S2:
The show needs to establish Bloodraven's character, who he is, for show-only people, before we get to The Mystery Knight (which will likely be adapted for Season 3), so he is the one who will find/catch up with Dunk and Egg in Dorne, sometime at the beginning of Season 2, to give Egg the signet ring.
With Bloodraven, there will be a letter -- along with the signet ring -- from Maekar telling Egg to stay with Dunk because of the Spring Sickness that is happening elsewhere arcross the realm, and that, even though he's angry that Egg ran off (again), his doing so, and his being in Dorne with Dunk, put him in a safer place to be than King's Landing is at the moment. And that will be the (on the surface?) reason why Bloodraven doesn't take Egg back to King's Landing with him.
This will all happen before The Sworn Sword plot kicks in (in likely Episode 1 or 2).












