A Game of Thrones
How we cite our quotes:
The broken sword fell from nerveless fingers. Will closed his eyes to pray. Long, elegant hands brushed his cheek, then tightened around his throat. (1 Prologue.109)
Power in A Game of Thrones often stems from violence. Basically, you can argue all you want with someone, but if that doesn't work, the guy with the more dangerous sword is going to win. And though we don't see very much of them, the Others certainly have some bad swords. What will any king be able to do against this sort of power?
"Please, Ned, guard your tongue. The Lannister woman is our queen, and her pride is said to grow with every passing year." (3 Catelyn 1.47)
Joffrey may have always been a bad kid, but the power he was given sure didn't help. (The secret is to threaten children with direwolves – that's what makes them good.) Same goes for Cersei: she probably started out proud, but the power of being queen makes her even more dangerous.
"Ten thousand, that would be enough, I could sweep the Seven Kingdoms with ten thousand Dothraki screamers. The realm will rise for its rightful king. […] They cry out for their king." He looked at Illyrio anxiously. "They do, don't they?" (4. Daenerys 1.34)
Ultimately, the game of thrones will probably be resolved by violence – whether its war or assassination (or a fun mix of both). But here we see that power can come from different sources of violence: either professional soldiers (the Dothraki screamers) or regular people rising up. Viserys thinks that he can combine the two into an unstoppable form of power.