Sorry Bee, but no matter how good this kid was, there's no way in Hell a group of 20+ warriors would let a thirteen year old join their ranks, to kill dragons. The youngest I'll have is 16 for him, which could be a bit insufficient for him, as magic power grows over time. You'd have to have him practicing magic from a very young age, so your bio will have to correspond with that. Learning from a Master or something - he'd probably be a bit reminiscent of a Jedi in terms of how his training went - non-stop, in order to get decent power that'll be helpful in killing dragons at such a young age.