This is one of the few times Spike is confident he's going to hell. He's lost his humanity, murdered innocents, and killed legends.
But all that is forgivable in comparison to this moment.
Her name is a sin on his lips and he'll likely be dead by sunrise if she doesn't leave now. But the mischievous smile on her face tells him she isn't going anywhere anytime soon.
His worry fades with an experimental kiss on her throat; it earns him a soft giggle in his ear.
It's worth the risk. Besides, his Nibblet knows how to keep a secret.