What if Spike didn't come to the Hellmouth with Drusilla in tow?  What if instead, he had a human lover that he had been with for several decades and perhaps she was dying of a disease like cancer.  The reason they came to the Hellmouth is because the woman's son is attending UC Sunnydale.

At this time Buffy and the Scoobies are still undamaged and even Giles has shown some sense of romantic sentimentality.  They view Spike's relationship as tragically romantic.  Angel is the only one who is openly scornful of Spike.

When Angelus comes out to play he makes a point of not only stalking Buffy, but going after Spike's human family as well.  In front of the whole crew Angelus rants about how Spike's ability to love humans is disgusting.  When Angelus kills Spike's lover, Spike makes a deal with Buffy to kill Angelus.

After Angelus is sent to hell, Spike stays to watch over his lover's son.  They have a solid father son relationship.  Perhaps the son wants to join the scoobie gang, but Spike protests because it's too dangerous.  From time to time, Spike helps out Buffy when she needs it.

When Angel returns from hell, Buffy isn't interested in falling into a relationship with him, and she puts no stock in his soul vs soulless argument because she's seen the extent of Spike's love without a soul.  Angel badmouths Spike whenever he can, and eventually leaves at the end of s3.

Spike grieves for his lover and it takes years for spuffy to develop.  Maybe not until S5.  However Buffy and Spike work together, and she goes to him for advice not only in dealing with demons but life stuff.  For instance, Spike might be integral in pointing out that 1) she can never have a normal relationship and 2) Riley has some serious inferiority issues.

Would like to see a spuffy friendship that develops slowly into an equal loving partnership.