Yes, I lost track of another one... swiss cheese brain strikes again... The Scoobs lose an apocolypse and send Spike back in time to try and fix it. Past Scoobs think Spike is nuts and make him live with Xan. Spike has to keep going back in time over and over and over again to try out different combo's on the doomsday box until he gets it right. The only way to keep track of the symbols on the box is to keep cutting them into his skin - part of the reason the Scoobs think he's crazy....
Mostly pre-slash up until the end...
Thanks in advance
PS thanks Sparrow2000 for your wonderful rec lists - lots of old favorites!
And found! You guys rock!
"Longest Day Ever" by shadowscast at Spanderfiles.