You guys think he could be the bastard, Aegon? Or do you think it's too late in the show to introduce a new big player? And if he turns out to be Aegon, do you think he will be a pro about it and work for Cersei against his kin? Or did he work his way up in Essos with the purpose of invading Westeros at some point anyway? Could he know about his father's actions and basically hate every faction?
Drax the Legend, Captain of the Fist, The Starwalker, The Jade Slayer
I think it's way too late to introduce another very important character. Probably too late to introduce even a slightly important character. There are only 6 episodes left.
And most people who watch the show do not read the books and have a hard enough time keeping track of the characters as it is. This would seem VERY out of nowhere for them.