We already know that Daenerys will be riding Drogon into battle — the big question is, who will be sitting astride the other two?
There's been a theory that the prophesied "three-headed dragon" — which Daenerys learned about in the House of the Undying — will be her, Jon Snow, and Tyrion Lannister.
The original theory says that Jon Snow and Tyrion are both actually Targaryens; Jon Snow being the son of Rhaegar Targaryen and Lyanna Stark, and Tyrion being the son of Aerys II Targaryen and Joanna Lannister. It seems likely that the three dragon riders will all have Targaryen blood, so if these two separate theories about parentage prove correct then Jon and Tyrion will start looking like very strong candidates for the role.
After the Season 6 finale, we're a huge step closer to that. The R + L = J theory was finally confirmed in Sunday's episode, which means Jon Snow is officially half Targaryen. We also saw his mother, Lyanna Stark, die in childbirth.
As one Reddit user pointed out after Sunday's episode, this means that all three characters have something very unique in common.