Spike absolutely picked up on it. At one point in his life, he'd absolutely abuse that fact, manipulate the other, too. It was tempting to do so now. Except he knew Buffy wouldn't approve. Even with her death, he still couldn't get her out of his thoughts.

So lost, as Dru had said.

"I don't want your blood, girl. But I'll help you anyway." Because he could admire a survivor like her. Relate in some ways. But also because she needed it, and he was trying to not be the monster he was in some ways.