It was the end of summer that Buffy had seen him.
He was standing far enough away that she almost didn't make him out. The tall, thin figure, wearing a torn pair of pinstripe pants and a blue collared shirt, standing beside his TARDIS. His skin glowed a faint gold color in the darkness of night, and his eyes looked so very, very sad, as they met hers.
He turned, and stumbled into his ship.
"Doctor, wait!" Buffy shouted, chasing after him.
But the TARDIS wheezed and groaned, and it had faded away long before Buffy had a chance to get to it.
Willow, Giles, Xander, and Riley all raced over to her, asking a million questions all at once. Why had the Doctor just left like that? What was happening? Why was he kind of glowing gold and stuff?
Buffy didn't answer. She knew.
He was dying. This was him saying goodbye.
She had been intending to spend the evening with Riley, but ever since she discovered what Riley had done to the Doctor at the Initiative, she had never wanted to confide in Riley about the Doctor. Hadn't even wanted to bring the Doctor up around Riley. She went home, instead.
"Your friend came to see you," her mom told her. "I said you were out, so he gave me this."
Her mom held out a thin white envelope for Buffy, one that was labeled with only the name, "Elizabeth" on the outside. Buffy took it, tracing her fingers across the lettering. Elizabeth.
She loved it when he called her that.
She loved the way he seemed to relish it as he said it, the way every single vowel sound seemed to overflow with affection. She loved the way his tongue tripped over the syllables, the way the sides of his lips seemed to naturally arc into a smile when he was done. A name she hated, so much, a name that wasn't even her own.
But when the Doctor called her Elizabeth, it was hers.
She opened the envelope, and examined the contents inside. She frowned, as she pulled out a small key on a piece of string. The TARDIS key. She examined the note that accompanied the key.
Give it to her right away. And tell her that when a third of the world ascends to the rooftops, she should wear it. Tell her not to take it off until the Prime Minister in the skies is dead. Remember, Elizabeth: a key is not always a key. And this one isn't, either. But it will keep her safe.
When Dawn comes, you'll know what to do.
— the Doctor
Buffy glanced at the key, confused. She had no idea what any of the message meant. At all. She put the key away, and tucked the envelope under her pillow. In the morning, she'd know what it meant. When the sun came up, she'd understand it.
The next day, the sun rose. And she had no idea what to do.
One week later, Buffy met Dracula. And a few days after that, she met Donna Noble.