On a technical level, this could be shorter; you could leave out the part about escaping the castle grounds and skip straight to finding her father’s allies. And please, you must must must guard against errors. In this context “parents” needs an apostrophe at the end: “parents’ slaughter”. “Fathers” should be “father’s”. “Saving her people” should be “save her people”. Remember, the smaller the space the worse errors look, and you don’t get much tighter than loglines.

Concept-wise, it’s a very good thing you put the Tipping the Velvet comparison in there – otherwise this runs the risk of looking like a warmed-over Snow White and the Huntsman (sorry, it’ the first thing springing to mind). I love the girl-girl angle (I assume that’s what you meant with your comparisons?) and your logline absolutely needs to work that in. How can you make it clear there’s a potential romance between Aewyn and the Amazon while retaining brevity and imparting the necessary information?

I’ll throw a for-instance at you. You can keep it or you can send it on back: “Princess Aewyn escapes the slaughter of her parents and begins raising an army, among which is (Amazon hottie’s name), a woman who stirs in Aewyn a passion for more than revenge.”

Now, is that a bit bodice-ripper-ish? Unquestionably. But hopefully it can get you started toward something more refined. It’s the kind of direction I think would best serve your concept, and it is a worthwhile concept.

A final note: “Aewyn” is a bit too similar to Tolkien’s ?owyn of Rohan.

For sure, Faustian Pacts are all about metaphor, but before you script this I think you ought to dive down into what you’re really trying to say with this story, and why you want to say it, why it resonates with you. From what you’re saying right now I don’t see any original angle that’d make this compelling. It sounds like a pretty standard “Don’t sacrifice what you need to get what you want” morality play, which is what Faust and all the deal-with-the-devil stories that followed was all about. Now if that’s all you’re trying to say, fine, but why bother? It’s been said and said and said. The only way I could see it working is if you really brought a lot of passion and an immense amount of skill to it to offset the fact that the audience knows how this is going to end as soon as it starts.

On top of all that, from the perspective of this website, I’d find it hard to craft a compelling logline for a story like this because distilling it is just going to serve up something we’ve all heard before. Have you read “Fair Extension”, in Stephen King’s collection Full Dark, No Stars? It’s a fantastic, terrifying take on the Faustian Pact that takes it in an unexpected direction. I just feel like there’s so much more you could do with a story like this than just what’s been done before – and so many times.