I'm just checking up on a story I read a while back that I don't know was completed. It was where Spike moves to Sunnydale before BTVS S1 and befriend Xander who's about 10 at the time. Xander isn't afraid of monsters b/c Spike will be there to protect him and Spike's minions took a shine onto him. Xander's practically one of them and Spike is like a caring guardian to Xander b/c his life is somewhat disappointing. It was still in its early stages.
A few of the scenes was of Xander trying to explain to him mom about Spike only to have her believe that he was imaginary. Also, Spike would visit Xander before he'd go to bed and tell him funny lies to get him to stay asleep (along the lines of "if you don't go to sleep you will get/have")