I like the idea of her being related/from Targon, but not on Mount Targon.
Aurelion taunts Soraka, "Twinkle, twinkle, little star, do you wonder what you are?"
This implies that Soraka does not know of her own origins, as well as implying Soraka is more then what she thinks.
Soraka is also the only champion who when Aurelion taunts them, does not look down upon. It doesn't imply he respects her either, but regardless.
The idea of Soraka being one of the original Aspects (Perhaps the Aspect of the Stars even), and not knowing it, would make for a very interesting plot line.
Overall, I just hope that Riot doesn't destroy how Humble and Caring Soraka is, and sticks with a plot/story that would do her character right.
I like the Tragedy, but I like the Bittersweet tragedy.