Taboo Fic: Buffy and Spike are half-Siblings, with the same father

It's a taboo fic, and Buffy have Spike have the same father, i don't remenber anything else I think the story only have 3 or 4 chapter and it's not finished

Anyone??

Is it Shelter by Sluggie?

http://buffy.adultfanfiction.net/story.php?no=544179999

do anyone knw what happen to Sluggie?

There's The Bond by dampersandspoons

In this Buffy/William are 'fraternal twins'...could this possible it? It has only 6 chapters.

Summary: Fraternal twins Buffy and William have a special connection that others are starting to grow suspicious of. Unaware that their behavior is wrong, Buffy and William become closer than they imagined possible. But will their secret remain hidden or will they have to face the consequences that come with the choices they make?

It could have been Fighting fate by Spikes_slayer08 but she removed it to do a full re-write

I cannot keep these threads open forever guys, so since the original poster hasn't denied that this fic provided is not the one they were seeking. I will assume it is one of the fics listed, and moving this to found.