And I was just too darn lazy to go find a pic of Athrun to compare to Kazuki... didn't remember I could just point to your avatar, duo!!
Lots of Fafner character designs resemble ones from Seed since they are from the same studio. I guess when you do something that works, you stick with it! 
NSP's link was really funny, and horribly accurate... change out the hair and clothes and you could have half a dozen characters from half a dozen different shows.
