This post contains mild spoilers for Season 6, Episode 2 of Game of Thrones.
In "Home", Tyrion fulfilled a lifelong dream and got up close and personal with some real, live dragons.
Just how close he got to them has made many fans excited about this old theory that Tyrion is secretly a Targaryen.
You see, once upon a time, Tywin Lannister was hand to the mad king Aerys – you know, Daenerys's father, who was killed by Jaime Lannister during Robert's Rebellion.
Aerys coveted Tywin's wife, Joanna, and took "liberties" with her on her wedding night. Some fans believe he took further liberties at a later date, and either had an affair with or raped Joanna, who got pregnant with Tyrion as a result.
The evidence for this theory is not quite as strong as it is for the practically canonR+L=J, and a big part of it is based on Tywin's deep hatred of Tyrion.
There's also the fact that Tyrion's hair is described in the books as "so blond it seemed white", which seems to line up more with the "silver-blond" hair of the Targaryens rather than the "golden hair" of the Lannisters.
On top of all this, he's been dreaming about and obsessing over dragons for his entire life – and, after "Home", seems to be able to ~tame~ them somewhat.