Smallville, Season 1

Clark:
Phelan came back after you were arrested. I got so angry that I grabbed him. And for a second, I wanted to... I wanted to kill him.

Jonathan:
But you didn't, right?

Clark:
Yeah, but I was close.

Jonathan:
Believe me, son, I know all there is to know about losing your temper. But you can't afford to do it. This is Phelan's game, and he will play your fear and your anger but you cannot let him get to you.

Clark:
I don't care. I won't let anybody hurt you and mom.

Jonathan:
And he knows that. But once you cross that line, there's no going back.