He wasn't worried about Buffy snapping and pitching a Slayer sized fit about his behavior. This was Buffy. She might have been one of the first people he'd expect to see swinging at his head if he did something terrible or out of line, but Spike also knew her well enough to be confident in where his limits and boundaries were. If he pushed her too hard, he'd know. Not just 'cause of the fist flying for his face, but because of the look on her face. That stubborn set of her jaw, the disapproving turn of her eyes, the unamused tilt of her head. Spike had seen none of those things. She didn't want to fight.
Or she did. But not in the way that involved punching his brains out.
"You do that and I might have to kick your ass, Slayer" Spike pushed back, moving forward with the tug of his shirt easily. The corner of his mouth immediately tipped upward into a pleasant little grin of his own as soon as he felt Buffy's fingers sliding underneath his shirt. It was a pleasant touch. As often as Spike had gone out of his way to mess around with other women in Buffy's absence, only she was able to make him feel the way that he did now. He was more than attracted to her. There was something inside of him. A burning, right where his heart would have been if it was still whole. She made him feel more than anything else in the world could and Spike wanted, more than anything, to make sure that she knew it.
He didn't give her that final needed push onto the bed just yet. Spike instead leaned forward and kissed her strongly on the mouth, pale fingers sliding into her hair. "You're not making a mistake," he informed her, lips brushing against Buffy's own, "you know how I feel about you."