starspeeder, I saw where you posted your blurb on the Fantasy Share Your Work thread. You wanted some feedback, & I'm happy to discuss it with you! (I hope it's ok to reply to you here)
I think you've made a great start!
I'd recommend editing as follows:
Inside Cover [Synapses (sp is 'synopsis'; but, this is really a blurb or teaser.)]:
Wren Duval was something that most of her peers weren’t[--(replace with a ':')] content. (Great hook!)
[But (Delete!)]as [add: 'a'] girl who had grown up in France during the Middle Ages, isolated from almost everyone, she couldn’t possibly know how lucky she was. (Great sentence!)
All that she knew was that she was happy. (good, good...)
[Unfortunately, the only constant in life is change.(Delete to tighten up your blurb & give it more impact.)]
In the months leading up to her 16th birthday, her happiness begins to fade as secrets [she didn’t mind staying secret begin to (? Delete)] unravel (add words: 'her world').
[Suddenly (Delete!)] thrust out of the only world she’s ever known and on the run from something she never believed existed, (awesome hook!)
Wren [starts to wish that she’s not (replace with: 'wishes she doesn't have to be')] the person she’s destined to be. (another great hook!)
If you make these changes, then your blurb should read:
Inside Cover Blurb: Wren Duval was something most of her peers weren't: content! As a girl who grew (another edit) up in France during the Middle Ages, isolated from almost everyone, she couldn't possibly know how lucky she was. All that she knew was that she was happy. In the months leading up to her 16th birthday, her happiness fades (another edit) as secrets unravel her world. Thrust out of the only world she's ever known and on the run from something she never believed existed, Wren wishes she doesn't have to be the person she's destined to be.
Writing blurbs and teasers can be both fun and frustrating, but I hope I've taken some of the scariness out of it for you.