This is purely a theory, and it has been floating around the web for a while already. It's not even in the books, but it kind of makes sense. Who is Jon Snow's mother? Check it out:

1. Jon Snow is referred to as Ned Stark's bastard. Who's his mom? No one knows.

2. Is it a huge secret? 

3. Too bad Ned died before he could reveal who his mother was. 

4. Fans believe that Jon Snow's mom was Lyanna Stark, Ned's sister.

5. Lyanna Stark and Rhaegar Targaryen are linked. Ned might not be the father!

6. Rhaegar kidnapped Lyanna, causing her fiance Robert Baratheon to go to war, who killed Rhaegar and became king. 

7. So this isn't some brother-sister love of course.

Watch the fan theory in this video by YouTuber Alt Shift X for a rundown of the evidence to this theory.

What could this all mean? Could Jon and Daenerys end up together?