[@pkken]Difficult, but not impossible. Aura is, as some of the other bios have mentioned, sort of akin to being a "chosen one" in a lot of respects. Prominent omens and signs tend to appear in the stars at the time the person is born, signifying their favor and destining them for greatness -- that sort of thing. So, if you have the ability to use Aura, you've always had it in you, right from your very birth. You are, in short, quite literally [i]built different.[/i]

However, just because one has been blessed with that sort of favor doesn't necessarily mean that using it comes to them naturally. It requires incredible focus, discipline, and commitment in order to manifest the power, which means that it could lay dormant for quite some time if the user has issues with confidence or self-control that serve as a stumbling block and prevent them from reaching the sort of zen state you need in order to pull the Aura out. In that sense, it's possible that their power could go untapped for a long time before they ever actually pull it off successfully, and others might not necessarily know or believe that they can use it.