Something happens, and Sam is teleported through time and space and universe. London, during the 1860s. There, he encounters a young woman we'll call Anne. I like that fanon.
Anne is convinced she's being stalked by demons. No one believes her, but Anne is sure of it. She says that the demons are targeting her because of her psychic powers.
Anne is a religious woman. She has been told that her psychic powers - her prophetic visions - make her a Devil child. She has even been told, by one of the "demons" hunting her, that she should simply give into her fate, and be evil. But she wants to be good. She wants to be pure.
Sam, of course, completely believes her about the demons. The two of them team up to protect her family. Ultimately, they fail. Anne's family is killed. Sam has his throat torn out by Angel (I don't accept the Angelus retcon). And Anne doesn't go by Anne anymore.
I did not realize until dreaming this bunny all the parallels between Sam and Drusilla. Very different endings, though.
I also considered having Sam and Drusilla encounter each other in the present day, with Drusilla as a vampire. I wanted them to have sex, since that’s what characters do in fanfiction, but Sam said no. So I asked soulless Sam. He sleeps with everything that moves, right? He said “Yeah…no.” I guess not so much with the sleeping with everything that moves. It's weird because I could see soulless sleeping with Faith, even during her evil days, but not Dru. Perhaps because with Faith, Sam would know where he stood: sex with no strings. Just the kind of thing soulless likes. But Drusilla's goals and motives are often incomprehensible to outsiders.