I read The Demon in Me and The Fallout and I'm really into immortal/demon Buffy fics - especially the D/B/S ones or B/S with Dru and Buffy being friends at least [since I <3 Dru].

You have probably read them but the Forever fics by spikeskat have a slayerdemon/immortal thang going on, no Dru that I remember though...
Forever by spikeskat sequel Forever Again

Primal has a slayerdemon aspect and Angel and Dru are in that fic too...
Primal by Kari Mouke

The Secret Slayer by maryperk
Something unexpected happens to Buffy on her first night in Sunnydale. Something that causes her to change her name and hide from the people that were to be her friends. What happens when a certain peroxide blond vampire rolls into town?

I'm pretty sure there is a slayerdemon aspect to these as well...

Blood Bound by DreamsofSpike
Early Season Four, immediately after Spike is chipped, Giles finds an ancient ritual that could solve their problem of what to do with the not-so-harmless vampire...but Buffy ends up getting a bit more than she bargained for in the process.

Chosen After Death by jackofspikes
Follows canon up until the Frat party with Parker then goes AU. The essence of the Power that was used to create the First Slayer has rested within Buffy since her first death at the hands of the Master - It's about to make itself known.

Elaisais by sabershadowkat
Buffy, Spike, Willow & Angel get sucked into a computer game. NB pretty sure there was a touch of S/A and B/W in this, I'm not sure but just in case that is an issue.

Yay! Thankyou

No problem, hopefully some will match what you are looking for. Who is The Fallout by? I don't think I've come across that.

It's by Kari Mouke. It's amazing and can be found here.

Fab, thanks.

I thought of another couple slayerdemony ones that fit I think. If you haven't already read it, this Kari Mouke has that vamp family aspect I think you like/were hoping for...

Taking the Initiative by kari mouke

Blood That Binds by Behind Blue Eyes
Set in Season Two, what if on Halloween Buffy dresses as a vampire instead of a coiffed debutante? What if she was found by Spike then? How will a mated slayer change their world?