The song is called sound of your heart by Shawn Hook and it fits perfectly with Emma leaving Hook in the underworld and them missing each other.
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Emma couldn't wait for the party. It happened every year and this time she was especially happy but also nervous. If anyone knew she had a tail, they would treat her differently, maybe even tease her. She took a deep breath and continued putting on her sparkly red dress. When she was done she twirled in front of the mirror. She looked beautiful. She decided to bring some extra makeup, just in case. She set out for the party with a happy grin on her face.