Tyrion. No, dude.
WARNING: Lots of spoilers about the Game of Thrones Season 7 finale ahead. Leave if you didn't watch.

Wow, a lot happened in last night's season finale of Game of Thrones, but let's focus on the most important thing first: DAENERYS AND JON BONED.

*very Etta James voice* At laaaaast.

And as they boned, Bran officially confirmed that Jon is, in fact, Aegon, the son of Rhaegar Targaryen and Lyanna Stark — aka heir to the Iron Throne ahead of his aunt/lover, Daenerys.

And, also while they boned, Tyrion lurked outside Dany's room and looked...well, none too pleased.

But why? Well, some think he might be going the way of Ser Jorah, and has fallen in love with his queen.

Others believe that he's worried about two rulers getting emotionally involved with each other mid-war. It could make for complicated alliances... though he seemed fine with it earlier in the season.
But the most convincing theory has to do with Tyrion's conversation with Cersei earlier in the episode. Remember, Cersei left the dragon pit and wouldn't call a truce with Dany after Jon refused to remain a neutral party in the war to come.
...so Tyrion went to try and reason with her. He entered into a room alone with his crazy-ass sister.
Shockingly, he survived. And the last thing we saw of their conversation was Tyrion realizing his sister is pregnant.
Then, suddenly, we see Cersei back in the dragon pit. And not only is she willing to call a truce, but she's willing to fight alongside her enemies to defeat the dead.
Obviously Tyrion made some sort of deal with Cersei, the only question is, what kind of deal was it? What if Tyrion revealed to Cersei that Dany can't have children, and promised that her child would be heir to the Iron Throne after Dany's death?
It would make sense. Tyrion does seem to be genuinely racked with guilt about Tommen and Myrcella's deaths...
HBO
This could be his way of making amends with his family.

...and he recently brought up the matter of succession with Dany.
Perhaps this is the face of a man who's really worried his queen is about to conceive, which would throw a pretty big wrench in his deal with Cersei.
And, unfortunately for Tyrion, we've been getting all sorts of hints this season that Dany might not be as infertile as she's been led to believe.
All sorts of hints.
Actually, Tyrion might be doubly screwed since Cersei doesn't seem to have any intention of keeping her promise of alliance.
And we all know how Dany deals with traitors.
THIS � WILL � NOT � END � WELL �
Source opera blog.