In regards to Tyrion....
This is more of a book reader theory but it was teased, IIRC, in the series. Going to tag it and would like opinions. Not really a spoiler, but could be.
In the books it's obvious and GRRM has stated as much, but the three main protagonists, POV characters, are Jon, Dany, and Tyrion. The show kind of got away from this in the development of Cersei and Jamie, which is great by the way, IMO. But since book one, it's really been the story of these three.
The symbol of House Targaryen is a three headed dragon. Dany had three dragons. Jon + Dany + Tyrion = 3. It's well known in the books that Tywin despised the Mad King. Hated him. It's hinted that the Mad King invoked some king's right and bedded Tywin's wife Joanna at some point. It's theorized based on that and some other conversations (I can't recall) that Tyrion may have been fathered by the Mad King. This also lends to Tywin's deep seated issues with Tyrion (that and Joanna died birthing Tyrion). Fan theory was that Tyrion is the third dragon, completing the three heads of the House Targaryen sigil.
Anyone think this old book reader theory still has wings? I tend not to considering one of the dragons is now a wight and also due to the diminished role Tyrion played in S7. But the three headed dragon symbolism, the three dragons themselves and the three primary POV characters, was a thing in the books. Just doesn't seem to be a thing in the series. Thoughts?