Little Swan Lost
Bilba has grown up the unwanted granddaughter of the Thain of the Kingdom of Shire but, as she rarely visits the palace, the relationship holds little meaning to her. Instead she focuses on her second year of college, her ballet career and her slowly burgeoning romance with Bofur, a crew member with her ballet company.
The same day Bilba is set to preform on stage for the first time with her company, the kingdom of Shire is anticipating another event. That very evening will oversee the political, arranged marriage between Thorin Durin, Crown Prince of Erebor, and an unnamed Princess of Shire (so unnamed because Bilba's grandfather is a paranoid bastard).
Bilba doesn't care about any of this, she hasn't been invited and has no interest in other countries, politics or other such machinations.
Just before she's set to preform, however, Bilba suddenly finds herself dragged from the theater and taken to appear before her grandfather at the palace.
There she is informed she WILL be participating in the wedding after all.
As the bride.
Whether she likes it or not.