Tyrion is the central cynical character, and cynical characters tend to survive stories. I think it’s partly because readers and authors alike identify with cynical characters the most. Tyrion is by far the most popular POV in the fandom and Martin says Tyrion is the character who is most like him too. “Death is mercy” is a common theme throughout ASOIAF, but if the solution to the cynical person’s cynicism is to kill himself or to get himself killed then it isn’t a very good or useful story. Life is full of challenges and adversity and that seems to be a constant across all individual lives. We can quibble about degrees of adversity. Yeah some people’s challenges are crippling starvation while other people’s challenges are beets (Tommo!). But not even the trivial challenges feel trivial when you’re in them.
So while the degree of adversity can be argued, relativity smashes the validity of the argument. The universality of adversity in everyone’s life cannot be argued. So you can’t have a problem-free life. It’s impossible. Then the best thing you can do is try not to be miserable your whole life while you encounter and deal with one problem after another. So the problems Tyrion struggles with are universally relatable in a lot of ways. How do we cheer the fuck up in the face of never-ending adversity?
Tyrion’s POV is arguably the fundamental through-line of the story. We journey with him to many of the most relevant locations in the world: Winterfell, Castle Black, Crossroads, Eyrie, King’s Landing, Pentos, Volantis, and soon probably Slaver’s Bay. He’ll be the first character to connect the West and East main narratives of Stark and Targaryen. Jon, Bran and Sansa have all reluctantly accepted Tyrion’s friend request and he’s positioned better than any other character to save the world of Planetos in the way that we mere dragonless mortals of Earth can ever hope to save our world, which is through diplomacy (broadly).
Apples and Dragons 