Tyrion is actually a Targaryen, too
Now that we know Jon Snow is a Targaryen, the next surprise sibling will be none other than Tyrion. This comes from the popular A + J = T theory, which means Aerys plus Joanna equals Tyrion. The books detail the Mad King Aerys’s obsession with Tywin Lannister’s wife, Joanna. According to the theory, Aerys impregnated Joanna, who died when giving birth to Tywin (similarly, so did two other Targaryan siblings: Jon and Daenerys). It would also explain Tywin’s final words to Tyrion—”you’re no son of mine”—along with his general disdain for his youngest son. And remember how chill Tyrion was with those little dragons?