Sweet Far Thing by Libba Bray (2007, Hardcover, First Edition)

The Sweet Far Thing is the conclusion to the Gemma Doyle Trilogy, where the protagonist, Gemma, must decide how to wield immense magical power and face the consequences of her choices. Summary Having bound all the magic of the enchanted "realms" to herself in the previous book, Gemma is now the "chosen one" with the power to shape that world. However, she struggles with the responsibility, hesitating to distribute the power as promised because she enjoys the control it gives her and wants to secure the future for herself and her friends in stifling Victorian society.

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