He had started learning karate when he was six years old. One afternoon, with no explanation, Ian Rider had taken him to a local club for his first lesson. (2.45)
Although Alex doesn't understand why Ian pushes him to learn self-defense skills, they'll come in handy when he's stuck in Sayle's evil lair.
"Tough luck, Double O Nothing," Wolf said. […]
The next thing Alex knew, the heel of Wolf's palm had rammed into his chest, pushing him back with astonishing force. (5.31-32)
Wolf is pulling a real macho move with this one. What kind of jerk would get violent with a fourteen-year-old kid? A big one, that's what kind.
He remembered his uncle's car, shattered by bullets. A man like this, a contract killer, would so the same to him. He wouldn't even blink. (6.73)
Alex has never seen violence like this before. Suddenly, things aren't fun and games—there are real stakes.
A single guard stood behind him, a gun in his hand. It was the sort of thing that Alex had seen a thousand times in films and on television, and he was shocked by how different the reality was. (12.22)
We can talk about violence in media until we're blue in the face, but the truth is that no movie can accurately portray what real violence is like.
The butler made an inarticulate sound and lashed out a second time. Alex got the impression that behind the livid scars he really was grinning, enjoying himself. (12.42)
In Stormbreaker, violence is typically used as a means to an end. Mr. Grin, on the other hand, seems to get violence for the sake of getting violent.
Alex looked at the figures, writhing in agony on the canvas. If he was right, the image would soon be repeated all over England. (13.3)
Chemical warfare is one of the most horrifying ways to inflict violence on innocents. As Alex observes, it would be a literal Judgment Day. Not cool, Sayle, not cool.
"Which means that you're not the saint everyone thinks you are, Mr. Sayle. A mass murderer. A bliddy psycho, I suppose you might say." (13.22)
Although Sayle doesn't see himself as a bad guy, Alex can see right through his phony rationalizations. There is, simply put, no justification for this kind of violence.
"But soon you will get tired, Alex. You will drown. […] The pain, I think, will be beyond the imagination of a child." (14.23)
Like Mr. Grin, Nadia Vole enjoys violence a bit too much. But while Mr. Grin acts as the silent killer, Vole seems almost giddy at the mere thought.
But Alex knew he couldn't do it. Whatever Alan Blunt and MI6 wanted to turn him into, he wasn't ready to shoot in cold blood. (15.3)
Although Alex is willing to defend himself, he has no desire to kill anyone. This sets him apart from every other character in the novel—in a good way.
"Believe me," he said, "it would be better if we didn't meet again. Go back to school. Go back to your life. And the next time they ask you, say no. Killing is for grown-ups and you're still a child." (17.78)
Yassen is the most feared individual in the novel, yet he has no particular love for violence. For him, it's just business.