I really hope Aymeric isn't related to the Dark Knights, because he's an official member of the Temple Knights and Dark Knights live to... purge, I suppose, corruption within the Temple Knights. I was also hoping to pick up DRK on my Au Ra alt ASAP (at 30) and if he's the class trainer for DRK that's impossible... though the possibility of being able to do so is suspect anyway, since Ishgard is sealed off until you complete 2.5.5.'s story.