Rick Riordan, The Last Olympian

Once she was gone, I knelt next to Annabeth and felt her forehead. She was still burning up.
"You're cute when you're worried," she muttered. "Your eyebrows get all scrunched together."
"You are not going to die while I owe you a favor," I said. "Why did you take that knife?"
"You would've done the same for me."
It was true. I guess we both knew it. Still, I felt like somebody was poking my heart with a cold metal rod.

Life Quotes And Sayings by Rick Riordan, The Last Olympian