OK, these are my attempts to meet what you are after, in some way at least(!).
A temporary reality change that Spike is fully aware of (and seasonal too, so yeah bonus!!)...
Fat Chris and The Wish by greyangel (not available on line, I have this in word)
AU. Playing with the time line, but set in season five, after the events in Crush, but without Drusilla coming back to tempt Spike to feed on humans again. It's Christmas and Spike is struggling with the Slayer's rejection. Sick at heart, feeling sad and lonely at a time of year when everyone around him seems to be in a relationship, Spike visits Willy's bar to drown his sorrows. While there, he meets a fat guy called Chris, who offers to grant him a wish. A short Christmas story full of simple Christmas magic. Buffy from an alternate reality comes to help during NFA...
Ripping Down the Walls by Peta
In another dimension, Buffy is friendless and fighting a battle against evil much too close to home, and it is one that she knows will almost certainly bring about her end. But will being sent to fight the evil in another world bring her death faster? Or awaken her to possibilities she'd never even considered? Set AU Season Three and during NFA.Dimension hopping and meeting other selves...
A Grain of Sand by always_jbj
Set in Season 6 somewhere around 'Life Serial' and goes very AR from there as slayer and vampire find themselves scouring dimensions. Will their search be in vain? And what will they learn along the way?The resurrection spell changes reality...
The Keeper of Truth by Trisha
"There's always consequences." Spike is proven right when Willow's spell brings Buffy back, years from where she's supposed to be. He'd be bragging that one up, if Spike of season 2 knew what the hell Buffy was talking about.Buffy is placed into an alternate reality but the two Buffy's are only in the same room very briefly at the end...
Pinch Hitter by dreamweaver
Buffy vanishes after stopping Adam and the Powers That Be bring over another Buffy from a parallel dimension to take her place.S6 swaps places with a future Buffy...
Learning the Dance by dreamweaver
An accidental wish makes Buffy switch places with her future self Buffy experiences childbirth of future other self during Normal Again...
The Peacemaker Chronicles by Nimue starts with
Twist on Normal Again (there are seven in the series in total)
This is going under the assumption that in Normal Again, Buffy was jumping between dimensions. Two coexisting realities. Also, theory that every decision we make creates a different path for us, and maybe a shadow of ourselves follows that path.A bit of a do-over, don't think the two Buffy's meet but it affects the current reality...
The Butterfly Effect by cousinjean
Five months after the events of "Chosen," a still grieving Buffy must follow a time-travelling demon back to 1997 (circa Season 2) Sunnydale to prevent him from destroying the timeline--and try not to destroy it herself in the process.S2 and S7 Buffy's swap, I think it is spasmodic (it has been a while since I read this)...
Actions Past by dutchbuffy2305
Sunnydale, 1997. Buffy makes a wish, with consequences...Buffy from the past and Buffy from the future will have to square their destinies and their lovers.
