There are two forms of answers to this: the Narrative reason and the Character reason. The Character Reason that Jon Snow bends the knee are several: When Tyrion tells Jon to bend the knee, he responds with “Why would I do that?” and that he doesn't know Dany. read more
The following contains spoilers for Game of Thrones season seven. IT'S HAPPENED, EVERYBODY. STAY CALM. Jon Snow has officially bent the knee to Daenerys on read more
So being Jon Snow, a deeply impulsive and hearty man he decided that he felt bending the knee was the right thing to do and he did it. To me that highlights the flaws and traits of Jon that we came to love and rue over the years. read more
Jon admits he hasn't done what she wanted, and bent the knee to her. Tormund then says something stunning: that he should do so. Between that and Dany's rescue of the team, the King In The North seems to have reconsidered. When he wakes up, Jon bends the knee to Dany — at least symbolically. read more