with Tyrion off-screen. They made a point to show Tyrion pull up a stool and say, "there are some things I want to ask you..." or something along those lines. That scene is a throw away if not for some information that Tyrion is able to use/reveal later, perhaps to betray everyone to gain favor with cersei? we didn't see all of their meeting together in king's landing last year and he's been relatively "off" since then... what with his hanging outside the door of Dany & Jon at the end of the season and "mis-judging" what cersei would do. then again, if he was doing so, why would she hire bron to try and kill them.

maybe they both survive the white walker war and as they celebrate, bron shoots one with the cross bow - he is dispatched only after revealing he was hired by cersei and the surviving brother fulfills the prophecy by killing her in revenge.