Spike's real name is William the Bloody. He got his nickname from torchering his victims with railroad spikes. Spike's sire is Angel. Whom he looked up to and though of as his "yoda". Ofcourse that was until Angel "got all soft" and aquired a soul.Spike hates Buffy, whom he refers to as "Slayer". When he tried to restore Dru's health, by draining Angel, Buffy ruined his plan and their battle (not to mention the burning of the church) resulted in Spike being put into a wheel chair. The restoration didi work, Drusilla was back to full strength.
When Angel lost his soulda and again became Angelus, he came back to be with Dru and Spike. At first Spike welcomed him and was happy to see him return, but when Angel started to take Dru from Spike, he got pissed.
It got to the point that he went to Buffy for help. He wanted to kill Angel and take dru out of the country. Ofcourse there was a deal involved. Spike was to help Buffy and free Giles and he got Drusilla. Spike did get Drusilla, but didn't stick around to help Buffy during her battle with Angelus.
Later on Spike came back, a broken man, when Drusilla gave him the boot. After a "good spot of violence" Spike decided that he shoudl go back and try to get Dru back, well he said he was going to "torcher her until she likes me again". Go Spike, after all your hip and young, just barely 200.