Who is that dragon at the end and who is riding it?
A brief scene in the final montage shows a dragon soaring over troops marching in Oldtown. That’s is Tessarion, the dragon we know from the books belongs to Daeron Targaryen, Alicent’s youngest son. Remember she was asking about him when her brother first came to King’s Landing, and was relieved to learn he is sweet and kind? Yeah, it’s that kid, but the showrunners cleverly keep the camera far away from Tessarion so we can’t see its dragonrider, as they likely haven’t cast Daeron yet.
