To be fair, I'd bet that only some of it is Fiona, and the other part is the power of youth. When I was 17/18, I was always being told by older people I was beautiful, but even then I knew I wasn't - good enough looking, but nothing outrageous. Fiona is definitely more beautiful than I was, in a way that is more instrinsic - good bones, athletic body and grace - so I can see how that combined with being on the cusp of adulthood might blow your mind. But the kids her age are immune to the effect of youth, so all you have to worry about ("all"!) is the effect of her own beauty. And personality.