Not the Settling Kind is a song from the books. It is Humongous and Tantrums' favorite song, and they sang it when they were married. It was also sung again in the end of How to Fight a Dragon's Fury.
I have never cared for castles or a crown that grips too tight
Let the night sky be my starry roof and the moon my only light
My heart was born a Hero,
My storm-bound sword won't rest,
I left this harbor long ago on a never-ending quest.
I am off to the horizon,
Where the wild wind blows the foam,
Come get lost with me, love,
And the sea shall be our home.