Jon Snow is still far from his Winterfell home, but Daenerys' dragon may have sniffed out his true roots. Does Drogon know Jon is a Targaryen on Game of Thrones? That face off was intense.
Khaleesi returned to her new Westerosi home and landed Drogon in front of Jon on the shore. The King in the North was unafraid (mostly), and didn't really have a reason to be. Drogon kinda liked him. Music swelled as the pitch black dragon gazed into Jon Snow's eyes — and who can blame him? Drogon practically curled up next to Jon and even allowed Jon to touch him. Honestly, it was quite reminiscent of the Hippogriff scene in Harry Potter and the Prisoner of Azkaban.
After the way Drogon took out the Lannister army, Samwell's rude family members, and almost torched Jaime I'm glad to see that he has some manners after all. The dragons have never responded to anyone this way. Tyrion Lannister might have gotten closer than others in Season 6, but, to be fair most of Daenerys' allies and advisors have been too frightened to go near the fiery beasts. Not Jon Snow, though, and fans should be proud of him. Cuddling up to a lady's pets is a surefire, no pun intended, way to get her to like you.
As far as clues go, Jon's Targaryen heritage is almost certainly why the dragon trusted him, but did Drogon figure out that he was part of the family? Was that a look of recognition and knowing, or just an instinct? It wouldn't be too surprising if Drogon was able to smell the truth in his blood. Also, if Drogon was so chill with Jon, is that also foreshadowing that he will one day ride a dragon? One staring contest sure has raised a lot of questions.
This How To Tame Your Dragon incident definitely spooked Daenerys. Ser Jorah's tension-filled arrival could not have come at a better time. While Jon and Daenerys may have said goodbye for now on Game of Thrones, Drogon and Jon's moment makes it pretty clear that their story is not over.