Caroline
Angel technically gave it to me for my birthday. Or, dream-birthday. Before we had the sexy times that took his soul away.
He killed my Watcher's girlfriend. Had it set up to where there were candles and music playing. Giles thought they were having a 'special night.' When he got up the stairs, he saw her lying on his bed. Neck snapped.
He attacked my friends. Took Giles - the Watcher - and tortured him.
Before Giles' girlfriend died, she got her hands on the curse. Translated it. Saved it to a floppy disk and we found it. She was a descendant from the gypsy tribe Angel was cursed by in the beginning. She also knew everything, but that's another story.
Angel decided to open the gates of hell. Or, try to. We had a plan to curse him again, bring back his soul. Willow was able to curse him, but it turns out the only way to close the gate was with Angel's blood.
He got his soul back. I killed him anyway. Apocalypse averted.