my most favorite part of Rick Riordan's series of demigods stories is the friendship between Percy and Annabeth.

Q : of all your Camp Half-Blood friends, who would you most like to have with you in battle?
A : Oh. Percy. No contest. I mean, sure he can be annoying, but he's dependable. He's brave and he's a good fighter. Normally, as long as I'm telling him what to do, he wins in a fight.