I wouldn't kill him, because he looked as frightened as *I* was. I looked at him... and I saw...
Astrid: It's a mess. You must feel horrible. You've lost everything. Your father, your tribe, your best friend...
Hiccup: Thank you for summing that up.
Hiccup: Why couldn't I have killed that dragon when I found him in the woods? Would've been better, for everyone...
Astrid: Yep. The rest of us would have done it. So why didn't you?
Astrid: Why didn't you?
Hiccup: I don't know... I couldn't.
Astrid: That's not an answer.
Hiccup: *Why* is this so important to you all of a sudden?
Astrid: Because I want to remember what you say, *right now*.
Hiccup: Oh, for the love of... I was a coward! I was weak! I wouldn't kill a dragon!
Astrid: You said *wouldn't*, that time.
Hiccup: Agh, whatever... I *wouldn't*! Three hundred years, and I'm the first Viking who wouldn't kill a dragon!
Astrid: First to ride one, though. So...?
Hiccup: I wouldn't kill him, because he looked as frightened as *I* was. I looked at him... and I saw myself.