My concept storyline

I've read some of the plots posted here, and also the comments and critics on them, and I decided to post my own concept/storyline/plot here too, since I think I could use some feedback to get it up to an avarage level. I don't care about blunt comments too much, but if you do post something along the lines of "it sucks" or "start over" please be so kind as to give a reason too.

Storyline:

A small world is plunged into despair when a prophet int he south makes a prediction about it's destruction by a soon to be born Half-Demon. When word reaches the king he spents a good year ordering his men around killing every Half-Demon they see, however, one half-demon baby, born in a rather isolated area to the north is sent to a different dimension by chance, just before news of the prophecie reaches there.

This baby (which accidentilly is our hero ) is found in this this other dimension and lives in an ophanage there, without the slightest clue who or what she really is, nor where she actually came from.

When the girl is 6, she is adopted by a woman named Asteriel and her 4-year-old daughter Sakura (a name that is prone to change in the future). Asteriel gives her the name Lythia and takes care of her onwards, as if she were her own child.

When she is 16, Lythia discovers, together with Sakura, that Asteriel has been hiding the fact that she is sick from them for a long time. They decide to serch for a cure. For about a year they try every medicine they can get their hands on, but none work.

Then word reaches them about a miracle flower (note: in this dimension there is no real 'magic' like you usually find in games and stories) that is said to posses healing powers. The now 17-year-old Lythia rushes to the cave where this flower is said to bloom immediately, accompanied by Sakura. When she touches the flower, Lythia is sent back to her original dimension again.

At the same time, multiple prophets in the (first) world predict the same: The Half-Demon they thought was dead is actually alive and the end of the world is soon to come. The king's youngest son, Aexe, persuades his father into letting him search this Half-Demon and kill it.

Aexe and Lythia run into each other and get acquainted. Lythia starts tagging along with Aexe, because she doesn't want to be alone in a world where she knows noone at all, though she doesn't tell Aexe this exact reason.

After some time they get along really well, but then they are separated and both learn of Lythia's true identity individualy. when and after they meet again certain events happen ( excuse my vagueness, but I think it would ruin the sequence in game if I told it here ) and Lythia decides to search for a way to defy destiny.

I'll post some more detailed info about Aexe and Lythia later, right now I'm just happy I typed all that without my internet crashing on me again like it did an hour ago when I had this all typed out too... By the way, my avatar is a part of a picture I drew of Lythia waaaaaaaaay back when the first ideas for this story started in my mind ^^;