Angel was one of Jumba's missing experiments during the three-year hunt for the experiments. She was also Stitch's date and original love interest. Angel and Stitch frequently dated, much to Lilo's envy.
Three years after the experiment hunt, one night, Stitch visited Angel, when the two heard Lilo and Skipper come under attack from Experiment 628. They rushed to the scene, only to find Lilo and Skipper unconscious in the aftermath of the attack.
Stitch and Angel rushed Lilo and Skipper back to Jumba's ship. There, Jumba explained to Angel and Stitch that due to 628's attack, some time after Lilo and Skipper awoke, they would inevitably transform into genetic experiments.
The next night, Lilo and Skipper transformed into experiments as predicted, leaving Stitch guilty and upset that he was not there for Lilo, despite Angel's attempts to comfort him. The next day, when Jumba tested Lilo and Skipper's new powers, Angel was tasked with training Skipper. While they were testing Skipper's karate skills, Angel found, to her shock, that she was becoming increasingly attracted to the now-experiment Skipper.
That night, Skipper awoke Lilo, Stitch and Angel to reveal that he had discovered Hamsterviel's hideout. The four spent the rest of the night and most of the morning planning an attack on the hideout, until Gantu and Reuben arrived.
They explained what had happened to Lilo and Skipper, before launching their attack on Hamsterviel's bunker that night. They split into two teams, with Angel's team going in the front door, and making their way through the bunker to the control room, where they met up with the other team.
However, once they reached there, they were confronted by Hamsterviel and his new experiment, Smasher, who easily shrugged off the experiments' attacks. Eventually, when Smasher wounded Stitch, Lilo's dark side (Athena) temporarily took control over her body and destroyed Smasher. Due to Lilo's jealousy of Angel, Lilo/Athena tried to telekinetically choke Angel, causing Apollo (Skipper's dark side) to take control over his body and attack Lilo/Athena.
As Angel took cover from the two duelling experiments, she used her song to give Lilo's good side the boost she needed to retake control of herself from Athena. When Skipper/Apollo, in uncontrollable rage, still attacked Lilo, Angel got between him and Lilo and tried to calm him down. But Skipper/Apollo, no longer recognising her in his rage, instead began attacking her instead, wounding her arm.
Just when Skipper/Apollo was about to finish Angel off, she smeared blood from her wounds across Skipper/Apollo's face, allowing Skipper to come to his senses and retake control.
However, just then, Hamsterviel fled the bunker and revealed a bomb that would destroy the bunker and kill everyone in it if they didn't stop it. Skipper determined that the bomb was touch-activated and sacrificed himself to stop it. But just before the bomb lifted off and exploded, Skipper confessed his love to Angel, and Angel confessed hers to him.
Angel and the others returned home and went to bed, with Angel left more devastated than anyone else. The next morning, Lilo, Stitch and Angel decided to go to the beach to lighten the mood, where Lilo and Angel used Lilo's telekinetic powers to help a reluctant Stitch swim.
Angel is a pink shapely female experiment with a strong feminine resemblance to Stitch and his primary love interest, with two long tendril-like violet-tipped antennae, violet-tipped ears, small eyelashes, white V-shaped symbol, slightly larger chest puffed out and dark pink Stitch-like back markings (originally upside-down heart-shaped or sometimes gone). She speaks with a soft Scottish accent.
Angel's song is a "special musical neuro-linguistic behavioral modification trigger". In a nutshell, Angel's song turns anyone who hears it evil. When Angel's song is sung backwards, it will have the opposite effect (turning evil people and previous experiments to good). Angel is also shown to be highly athletic and skilled with karate.
Experiments who were created after Angel are immune to her song.