For weeks, Jon Snow, King in the North, stood tall, refusing to bend the knee to the Dragon Queen because he knew his people were proud and adamant- none of them thinking well of the Targaryen.
However, how is it that in the last couple of episodes he seems to pull a 180 and pledges his allegiances to her after almost dying on the wight hunt north of the wall, which saw the death of Viserion, one of Dany's dragons? Is it guilt? Or right before he died, did he realize what the queen means to him?
Daenerys comes to rescue Jon Snow and the rest of the party (still get chills with this scene) pic.twitter.com/gVUMUPW1RS— targaryen (@SavaEleonora) May 29, 2018
We're led to believe it's a combination of all the above, along with admiration that she knew the risks and came, when she could have turned around, and she still decided to save them all. At least, that's what seems to be the reason behind him surrendering the North to her.
However, theorists believe this is a veiled power play by Jon. Forget his love for Daenerys and think about the politics behind it all. Jon isn't blind to all of it, having been killed by dissenters back in Season 5. He's aware his extended presence in the enemy's territory will sow dissent and he's well aware that Littlefinger was not to be trusted.
According to the theory, Jon took everything into account, even Sansa's betrayal, and thus handed over the North to Daenerys, hoping that Sansa would take over Winterfell and ultimately his family lands would still be under a Stark.
That's a nice theory, but let's stop for a second and realize Daenerys pledged to fight for the North and protect it for nothing besides the chance to help defend it, as she knows her dragons are the only big guns they have. She did all this BEFORE Jon gave her the North, calling her his queen.
I do agree that Jon knew of the intrigue, but at the same time, he wants an ally. The fact that he's in love with the queen and that he's pledged the North to her seems more of a smart thing to do than anything. So much so, that even Littlefinger acknowledged their power together.