The main evil characters are Drusilla (Juliet Landau) and Spike (James Masters), a vampire couple that loves each other very much - until Angel gets bad. Then Drusilla leaves Spike and returns to Angel. She was made by him after he had killed her whole family and tortured her until she went mad. He killed her the night before she wanted to enter a convent. She travelled through Europe for a long time, killing everything that got in her way. Then she was nearly killed herself, but saved by Spike. From that moment onwards they have been together.
Now they are in Sunnydale, trying everythig to kill the Slayer.