It's just another boring ordinary patrol until she spots Spike between the gravestones in Restfield Cemetery. Certain that he must be up to no good (what else would evil, soulless vampires be up to?), she follows him.
It takes a while before she realizes he's known she was there all along and is leading her on a wild goose chase. By then they've walked across half the city and have ended up almost all the way out by the old factory. She's furious and quickly catches up with him, intending to give him an earful of her mind and maybe also a noseful of her fist. Just as she puts her hand on his shoulder to stop him, there's a sharp cry to their left.
It's coming from the woods on the other side of the street. They exchange a glance and take off running.
In a clearing, they find the source of the noise. There's a great big demon there, a shimmery-skinned, pus-dripping piece of nasty with four horns and a scorpion-like tail she'd rather not go near.
It's fighting an angel.
Buffy has never seen an angel before. Didn't even know they actually existed until now. There's no mistaking it, however. He's beautiful in an otherworldly way: curly golden hair like a halo around his head; stark naked, but built like a Ken-doll so there's nothing to actually see; flawless skin. And oh yeah, the humongous wings. It's hard to look directly at them, they're so blindingly white.
Next to her, Spike has gone all tense. She can't tell whether it's because of the dangerous looking demon or the angel. Perhaps both.
They watch the fight. The angel holds his own with a great big flaming sword against the demon's attacks. Neither appear to be winning. There's a gash on the demons thigh though, so it was clearly it they heard cry out earlier. The wound bleeds a mustard-colored goo.
Seemingly understanding that it won't win, the demon hisses and makes one last swipe with its deadly tail before fleeing.
"Oh no you don't," she cries and takes off after it.
With Spike and the angel on her heels, she darts between the trees and tries to keep her eye on it. It's fast. In the end she gets lucky when its tail catches in the nearly buried remnants of a chicken-wire fence and it goes face-first in the dirt. The few seconds it takes it to begin getting up are all she needs.
She's only got a couple of stakes and a dagger on her, but that doesn't stop her. With a jump she's on its back and cheerfully stabbing the dagger into its neck.
"Don't kill it!" the angel yells.
"Why not?"
"It's no use to me dead," says the angel, and his tone implies duh, she should have known. Angels weren't supposed to be snarky, were they?
She yanks the dagger out and climbs off the demon (her jeans are completely covered in pus, great), muttering to herself and trying not to breathe in the stench of the weird blood.
The angel touches the demon and it disappears. Seriously, just disappears.
"Who the hell are you?"
"How apt," he says and smiles. "I'm Lucifer."
His smile is so beautiful it aches.
"You're the devil?"
Spike makes a warning noise but she ignores it.
"Please don't tell me you're here to end the world or kill me or something like that."
"Merely passing through," he assures her and smiles that too-beautiful smile again. "A tourist in your world, if you will. That demon was a runaway. I was bringing it back."
"Not sure I believe that," she says, but refrains from snorting. Probably not a good idea to piss him off. "Thought you were supposed to, like, have horns and a pitchfork."
"That's a different one. There are many Hellgods."
"Hellgods?"
"Devil is just another word for Hellgod."
"Right. You're welcome, by the way."
"Ah, yes. I do appreciate your assistance. Here." He makes a complicated gesture with his hand and she feels... something... wash over her. It's like a breath of air, only not. "One boon. Call my name when you want to use it."
With that, he, too, disappears. No fancy flying-off-into-the-distance exit. He's simply there one moment and gone the next. Creepy.
"What's a boon?" she asks Spike.
"Means he owes you a favor."
"Yech, I can manage without the help of evil creatures, thanks." She gives Spike a pointed look and stalks off.
A favor, huh? She vows to never use it.
Eight months later she's more than happy to eat those words after Quentin Travers reveals Glorificus is also a Hellgod, Spike nearly dies protecting Dawn's secret and Tara is rendered insane. Spike convinces her to call on Lucifer and he appears in a flurry of white feathers. (Anya carefully gathers them up afterward, apparently they're very valuable.) While he claims he doesn't get involved in fellow God's business, he does put her in touch with Glory's brothers, who have no such squabbles.
Turns out Hellgods? Huge on the sibling rivalry thing. And Magnificus and Majesticus really, really don't want her to return.
And so she finds herself up on Glory's tower with Spike, fending Doc off of Dawn while Magni and Jester keep their sister occupied below. When Doc's taken care of, she rushes down to deliver the final blow with Olaf's hammer as they hold her down.
The Hell-Bitch is gone. Tara's mind is restored. Nobody died.
The weight of the world is no longer on her shoulders.
Spike comes down carrying Dawn in his arms and she's so overjoyed and relieved she kisses him. In front of everyone. She decides the look on his face is worth the inevitable intervention and stoically refuses to acknowledge the whole it-feels-amazing-to-kiss-him side of things. Maybe she'll deal with that later. Maybe not.
The End