The Pet Dragon - Dragons of Westermere, #1

The troglodytes below the peaceful kingdoms of the known world are stirring again, hungry to rekindle ancient enmity between human, elf, dwarf, and halfling. If their machinations succeed and war returns, the ancient troglodyte king will be able once more to return to the surface, and start a war of conquest that will change everything. His plans are finally underway, after centuries of preparation, and a chain of events has been set in motion that will unleash a storm of bloodshed across the dwarven mountains, elven forests, human cities, and even the farms of the halflings.
Completely unaware of the terrible plans that are reaching fruition, Willowtide is a young elven girl living in a peaceful elven city among the trees. One day she sees a dark shape in the sky, and driven either by impulse or destiny, she embarks on a journey to save and befriend a dragon, a journey that has huge and unforeseen consequences for her, her friends, and the troglodyte king's plans for the entire known world.