She comes to his crypt for a crisis and sees him dancing alone.
He's dancing to Marvin Gaye's "Sexual Healing". Mom-music.
His knees bob together foolishly, and she remembers he lived through the Roaring 20s. He throws his arm up in the air and she realizes that in the '70s, when Angel was skulking around sucking rats, Spike was scarfing second-hand Quaaludes at Studio 54.
He mouths, "Let's get it on" and she sees that curl of his lip that goes with the white hair and the black leather; she was just barely born. He hasn't caught up to the Oughts; all that time behind him slows him down. He's older than the slow guys on the moon, older than Disneyland, older than the Zapruder film, older than Mae West saying "Come up and see me sometime".
But she's come to him, nevertheless.