Once Upon a Time
After much imagining since the last Once manip of Buffy being a princess, I've come up with a really fun idea.
So yes, Buffy is a princess forced to run away from her charmed life and family when she's chosen to be the Slayer of this world. The thing is, she's not just any princess. She is, in fact, the close sister of Princess Belle. Desperate to keep her sister out of danger, Buffy takes measures to insure her family thinks she's dead or that there's no chance of her return.
Reunion with Belle would be lovely, and with one of the handsome characters of your selection- come on, you know Buffy couldn't help herself from falling for a semi-bad guy. Jefferson? Hook? Frankenstein? Falling for men no one would expect seems to run in their family, after all. She's hardly judge her sis. In fact, bonus for Buffy having some kind of camaraderie with Rumple in previous years, never knowing he held her sister, and Belle never suspecting her dead sister isn't gone and is even consorting with the man she's falling in love with.