First a hug for a real RP question.
Well the problem is you need the "dragon blood" to gain the powers you gain. But your character does not need to know he has a past ancestor who was a dragon. I would suggest writing in a dragon who has befriended your family for generations, and has taken a liking to you. And through his/her teachings you learn how to activate the inner powers that lay dormant in you. Or your character could have seen another dragon disciple, and feels an inner strive to attain that type of power. But it really depends on how your DM feels on that. And anyway that is a fifth level character startup, you can use that time to use the ideas I put in. And if your DM fusses just tell him/her "very few races are 100% pure blood in the long run, my character could have unknown dragon blood in them."
I hope that helped. I never really played one myself, I am more of a rogue, cleric or wizard man myself.
And if you want more help with that, go to
www.dndonlinegames.com it is a great online roleplaying site. It has a lot of players, DMs and an online dice roller for posts. I go by the same name there as I do here.
The victories from those skilled in warfare are not considered of great wisdom or courage, because their victories have no miscalculations
- SUN-TZU