It only made sense to me recently why Angelus suddenly hated Spike so much. One moment, they were best friends and they were happy to kill people together and the next, Angelus tears Spike down where he knows it will hurt him the most and then it is downhill from there. Why?
Their big fall out happened after a carriage ride after a happy night of slaughter.
The men were talking about Drusilla.
Angelus saw Drusillla has his masterpiece. She is the embodiment of the fall of man. She was pure. She was his opposite and he took her and twisted her. He bent her and broke her and then cursed her with immortality so that all would see his work and marvel at his skill and fear his wrath.
Spike, however, was a poet. He looked at Drusilla and he could still see the woman that she was when she was a human. He saw her childlike qualities as the shadows of her purity and as part of the mark of her insanity. “It’s like she’s still got a bit of a child in her.” One doesn’t get more pure than being a child.
This is what pisses off Angelus. Spike looked passed her insanity the way no one else did. He looked passed the mark Angelus left on her and told him, point blank. “I still see her, you didn’t destroy her as much as you like to believe.”
I think that’s why Angelus hated Spike. I think that’s why he worked to sabotage Spike and Dru. Not only did Spike understand her and give her companionship but they really loved one another.
Spike made Dru happy. Angelus’s masterpiece was in her suffering.