All of them, though Amaya and Zero are a little more crazy to explain than Hunter's.

http://phoenixwing.weebly.com/hunter-jorgenson.html That's Hunter, the Jade Dragon Slayer of Dragon Fang.

http://phoenixwing.weebly.com/amaya-tamashii-amaya-van-isis.html And that's Amaya Van Isis, the Ice Dragon Slayer of Phoenix Wing.

They're currently the only two active Dragon Slayers in the RP. Read their backstories and see if that helps.