The Season 7 finale of Game of Thrones left fans with as many questions as answers. Fan theories have been flying around the Internet, and some of them are truly mind boggling, like the theory that Tyrion betrayed Daenerys in his meeting with Cersei. It seems unlikely that Tyrion would suddenly side with his hated sister—especially against his beloved Targaryen queen—but there’s actually a lot of evidence to support a Lannister collusion. After all, the finale demonstrated that off-screen conversations can have powerful implications for certain characters. Just ask the late Lord Littlefinger.
Fans will have to wait at least a year (and likely longer) for more Game of Thrones. That’s a long time to go before unraveling the series’ remaining mysteries... but hey, that's what fan theories are for. If Tyrion really did lie to Daenerys, and conspired with his sister, fans can expect to get the answer early in Season 8. With only six episodes remaining in the series, it's more important than ever to take the time and understand the subtle implications and machinations of Game of Thrones.
The Season 7 finale of Game of Thrones was influenced by a number of important, off-screen interactions. Arya and Sansa plotted with Bran to execute Littlefinger. The Night King made a plan of attack against the Wall. Jon and Daenerys agreed to get down. The audience, of course, saw none of it. However, the most important bit of missing dialogue may have come from a conversation that was cut short.
Tyrion Lannister met with his sister, Cersei, in one of the most tense scenes of the season. After some verbal sparring, the siblings found common ground when Tyrion discovered Cersei’s (alleged) pregnancy. However, immediately at this moment, the scene cut away, The audience is left to guess what happened next, only sure that neither party was finished with the conversation yet.
Cersei denied Daenerys Targaryen’s truce, which is why Tyrion sought out the risky conversation with his sister in the first place. At first, Cersei wouldn’t agree to a ceasefire without some explicit promises from Jon Snow. But, after speaking with Tyrion, she had a completely different position, agreeing to fight alongside Jon and Dany in the Great War.
Even though Cersei was secretly lying about the truce, something happened during her meeting with Tyrion that made her change her public position. Something—someone—convinced her it was a good idea to lie her way out of the situation.
Multiple Reddit users pointed out that earlier in the episode, Tyrion had already given his thoughts on the morality of deceit. When Jon Snow’s earnest northern honesty nearly doomed the realm, Tyrion lamented, “Have you ever considered learning how to lie every now and then? Just a bit?”
Fully on board with the whole “Great War to save the realm” thing, Tyrion doesn't mind lying if the ends justify the means. Perhaps Jon wasn’t the only person in King’s Landing Tyrion advised on the benefits of white lies that day.
It would be out of chraracter for Tyrion to outright stab Daenerys in the back. He seems to truly believe in her potential to create a better world, and he isn’t switching his allegiance to Team Cersei anytime soon. However, Tyrion could have betrayed Daenerys by telling his sister to lie, as theorized by FacelessGreenseer on Reddit.
Now that Tyrion believes in the threat from the North, he knows the most important thing is for Dany and Jon to focus on the White Walkers. In this light, it makes sense that he would be fine with Cersei faking a truce. Tyrion’s betrayal could have been as simple as telling Cersei his queen was gullible. After all, all it took was a half-hearted speech for Daenerys to believe Cersei would join the northern campaign. Tyrion might not care if Cersei holds the southern kingdoms for a few extra months while Jon and Daenerys deal with the real threat.