Ah, we finally have a Rinoa fanboy to claim the prize. Yes, it's the lily of every man's heart, Rinoa. I was a bit obscure with the clues because, well, Final Fantasy characters are normally guessed instantly.
1. Relations with my family? Awkward. - Rinoa really is a teenage rebel.
2. My upper-body strength is quite good. - She hangs on at Galbadia Garden for freakin' ten minutes or so in a precarious pose for Squall to come rescue her. Plus, thanks to the DL stat topic, I now know that Rinoa's base Str is inexplicably high.
3. So, according to this piece of evidence, I participated in that mission? ...no, that can't be right, my memory is fine and I'm sure I wasn't there. Must be mistaken, or from an alternate universe, or something. - In the FF8 demo, Rinoa is in the Dollet mission rather than Selphie. I remember seeing screenshots from that and thinking WTF when I actually played the game. The actual clue here was "my memory's fine," as this isn't true of many in FF8.
4. Both my left and my right are exceptionally powerful - as my disliked relative can attest. - Rinoa's Triple Triad card has an A on both the left and the right. And like most in FF8, her dad General Caraway has her card.
5. I can't see in the dark, and it would be quite naive to think that I could. Though I can fly. - Rinoa is a Timber Owl... but not that kind of owl.
7. Who would have expected that a sweet angel like me could deliver such random destruction in battle? - ANGEL WING HYPE.
8. ...though I don't really get to unleash that magical destruction in the DL, alas. I suppose I'm stuck using my earlier battle form. - Without magic, Angel Wing is really bad, so Wishing Star hype?
9. I have cause to draw a fair amount, but I'm not an artist. - FF8.
6. As I look back upon one of the darkest and lowest periods of my life, I see one fewer set of footprints by the sea than perhaps would be expected.
10. I guess that would be because someone carried me. How romantic! - Squall carrying Rinoa on the bridge from Fisherman's Horizon to Esthar, which she doesn't remember at all presumably.