Actor Lino Facioli has played Robin Arryn since Game of Thrones Season 1. He is now 18, and showed up again in the series finale. It took me a minute to place him. I had just enough time to be confused, wondering why they were adding this new character in the final -- oh my god that's "Make the bad man fly" Robin Arryn!
So ... should we take this as an argument for breastfeeding into adolescence or what?
Some fans were thrown off by seeing grown-up Robin. It was somewhat like fans being uncomfortable watching Arya Stark having sex with Gendry -- these are characters we still see as kids, even though they are now technically adults. But more than anything, it was like Harry Potter's Neville Longbottom. Remember how Matthew Lewis started the Harry Potter films looking nerdy-sweet and exited the series with the ultimate transformation? That just happened again, and fans noticed.
Here's a direct comparison of Robin/Neville transformations:
You may recall Harry Potter author J.K. Rowling's unsettled reaction to seeing sexy photos of Matthew Lewis in the 2015 issue of Attitude magazine. She tweeted to him that it wasn't as bad as watching Harry Potter star Daniel Radcliffe get naked in Equus, but it was close.
As for British–Brazilian actor Lino Facioli, he returned as Robin Arryn for a key scene toward the end of the Game of Thrones finale. No plot spoilers here, but maybe seeing him was distracting enough for fans that they didn't notice the water bottle (or two) left in that same scene. Not that everyone was impressed by grown-up Lord Arryn: