It's driving me crazy that I can't find this fic....Buffy and Spike's teenage-ish daughter somehow mets up with a married, 30-something-ish Connor who I think is a architect and denying he's The Destroyer. They have an affair and at some point Connor's shrewish wife shows up. For reasons I don't remember, Connor falls through a portal and eventually comes back feral.

Angel, and a married Spike and Buffy are supporting characters.

And there's at least 1 sequel.

That's Addie Logan's story, part of her Daylight series. Only on AFF. I can't post the link from here, but it's there.

I had her in mind but maybe I didn't dig far enough into the sequels. Will go look again. Thanks!

Oops! Wrong emoticon. Meant this one