The protagonist in A Game of Thrones is Ned Stark. He's a skilled fighter, and wants what's best for his family. He has to much honor as it ends up killing him at the end. Ned is a fairly static character throughout the story, only learning right at the end to be cautious in who you trust before he dies.
The Antagonist in A Game of Thrones is by far Cersie Lannister, dead King Robert's wife and Jofferey's mom. She arranges King Robert's death, has Ned arrested, and puppets Jofferey to her advantage. She does have a reason to be icey/ cold, her son is constantly being threatened. She does a lot to protect her children.
The theme of A Game of Thrones is that actions have consequences. An idea that is constantly referred to in the book is that the power struggles are a game, kinda like chess, hence "A Game" of Thrones. Chess is very much a mind game, with players sometimes having to make sacrifices and planning moves a few turns ahead. All of these strategies are to reach the final goal of winning, and all of the choices you make in the end can come back to help or kick your butt.
"The direwolf graces the banners of house stark" (20). In the start of the first book the children of Stark, Robb, Jon, Sansa, Arya, Bran, and Rickon all receive a baby direwolf. These wolves throughout the book are a source of strength for the children but also show that house Stark is not to be messed with. They also show the growth of the characters and kinda foreshadow some things.
"I am so sorry my love Jon Arryn is dead." (25). Jon Arryn the previous hand to the king dies at the start of the book where you also find out that it was murder but no one knows who. This leads Ned on a search through King's Landing on a trip to all of Jon Arryn's last few outings. A point that is stressed strongly is that Jon Arryn was here before he died. Ned ends up being arrested and dies a few days later.
"Heward was hacking at the hands that had seized his bridle when a spear caught him in the belly." (383). The dramatized voilence in the Game of Thrones books gives them a very cold and painful mood. Especially when you later find out that people like Heward had a wife and kid's.