Thalia Grace
Thalia is a very skilled fighter and as she stated in The Titan's Curse; she can always beat Luke in a battle (which Percy has only done once). It is also mentioned throughout the series that she has a punk sort of style, hates Barbie dolls, and likes Green Day. She is always listening to rock bands and is into the punk subculture. Annabeth compares her to Percy, telling him, "You guys are so alike it's scary. Either you would have been best friends, or you would have strangled each other."