Disclaimer: Buffy the Vampire Slayer and Lord of the Rings belong to their respective creators, Joss Whedon and J.R.R. Tolkien.
Author's Warning: major AU. Absolutely non-canon.
The happenstance meeting with Strider stayed with her for a long time. She thought about their conversation together for weeks, wondering if it had seemed as weird to him as it had to her. She'd felt so strange, sitting there by the river with him, as if some huge weight had lifted from her shoulders, as if her heart had lightened and she'd been able to talk to him as she wanted and not as others wanted her to. He'd never even questioned why she was crying by herself in the middle of the woods, not as if he didn't care, but more as if he'd been able to just look at her and see what was wrong, as if he could look straight through her and into her heart.
Buttercup did look for the golden-haired girl Strider had talked about. She kept her eyes open wherever she went in the Old Forest, and everywhere else in the Four Farthings. Once, she even went right up to the fringes of Bree, watching the Big People going about their business from the safety of the treeline, but no one she ever saw looked anything quite like what Strider had said.
For a while, she hoped to meet him again, at least once, and spent more time in the woods near Withywindle than ever. But he must have meant what he said, because she never did see him again, not near the Withywindle or in the Shire.
When she was fourteen years old, near fifteen, Bilbo told Buttercup that he wanted to make her his heir.
He said it at supper, when the whole Brandybuck clan was gathered at table. When he'd finished, his cup in hand, everyone turned to stare at Buttercup.
Buttercup stared at Bilbo. “Heir?”
“My sole heir,” said Bilbo, “to inherit Bag End and all else, after.”
“After?” Buttercup was confused. “After what?”
Bilbo's mouth opened. There was a cough or two up and down the table. “Well, er—after I am gone.”
“Then,” said Buttercup, “what's the point?”
There was another little silence.
“The point?” said Bilbo.
Buttercup was exasperated, and slightly panicked at the thought that Bilbo might be going somewhere, like Strider. “What's the point of having Bag End if you're going to go away?”
Merimac looked down into his cup, smiling to himself. Daddy and Mommy looked at each other, and everyone else made small noises under their breath.
Bilbo's expression was passing strange; his eyes looked wet. He cleared his throat, adjusted his waistcoat, and said, “Well, Buttercup, you'll have to find that out for yourself, as I've made up my mind. You'll have Bag End, when I've gone. I'll say it again, before all of you: I have made Buttercup my sole heir, and all that I have will be hers.”
Buttercup hated the thought of Bilbo going anywhere. Wasn't it enough that Strider had gone away, when she'd only just discovered him? For several weeks after the announcement, Buttercup went to Bag End every day, hurrying over right after breakfast, just to make sure Bilbo was still there.
All the Shire talked about the adoption. They said again and again what a lucky girl Buttercup was, to first be taken into the Brandybuck clan by the Master of Buckland himself and then to be heir to the eccentric Bilbo Baggins, whose tunnels were said to be full of gold. People whispered to each other that life was making up late for all the tragedy she'd suffered early.
Buttercup knew that though Mommy and Daddy loved her very much, the adoption was a welcome relief. It had always been assumed that Buttercup would eventually become the chief hunter of Brandy Hall, but the title was a mostly empty one. She would never have come into any significant property or inheritance, being only a foster and there being so many blood relatives before her, and though Saradoc wouldn't ever have turned her out or done anything less than take care of her, she would never have had any money of her own. Mommy had been worried for years about what would become of Buttercup later, had been carefully hoarding what she could to give her a proper dowry.
Now that she was Bilbo Baggins's sole heir, however, to have Bag End, one of the oldest and most well-appointed smials in the Four Farthings, and inherit his considerable assets after him, Buttercup stood to be one of the most eligible girls of the next fifty years. She knew this very well, mostly because Aunt Amaranth wouldn't stop telling her and anyone else who happened by.
All of a sudden, she was a marriageable girl. Mommy explained it to her, one night as she sat combing Buttercup's hair. Everything was going to change, had changed. She was not only the foster daughter of the Master of Buckland, which was no small thing to begin with, but now she was also an heiress. There would be offers, sooner or later, and she would be expected to accept at least one. She didn't know why the thought depressed her so much, or why, when she remembered hair as black as night and eyes as gray as the clouds in a storm, she was filled with a deep and gentle regret.