Even if "The Iron Throne" hadn't the final episode of Game of Thrones, there would have been a truckload to process. It only adds to the deluge that this was the last new episode of Game of Thrones you're going to see, even if you're looking forward to the prequels or the Game of Thrones: The Last Watch documentary.
There was the death of the Dragon Queen, Jon Snow being sent to the wall, Bran Stark being crowned king, Arya Stark going west of Westeros, and a jaunty new king's council being assembled. Despite all of that, a handful of people found something else quite eye-catching. During the meeting where Bran would be named king, there were many characters present who have gone MIA for seasons at a time. For instance, Edmure Tully was back (and getting put in his place by his niece Sansa). Among those at the meeting was lil' ol' Robin Arryn.
If that's not ringing any bells, you might remember him as the annoying little boy on the cusp of his teenage years who was still breastfeeding from his mother Lysa Arryn, sister of Catelyn Stark and wife of the murdered former hand to Robert Baratheon, Jon Arryn. He has been seen being a tool of Littlefinger and screaming that he wants to see bad men fly out the Moon Door. He was a twerp and no one liked him.