- "We like our thrills more refined. Pain. Hate. Fear. Like the finest wine."
Pearl and her brother Nash were powerful half-demons who were in the service of Twilight. They drew strength from primal emotions and could generate weapons of energy as well as blast green beams from their eyes. Their mother was a human who intentionally bred with a demon, believing that their children represented the "next stage of evolution." Trying to impress their master, the Pearl and Nash massacred an entire Slayer squad with the exception of Nadira. After the downfall of Twilight, Pearl and Nash were recruited by Whistler to take vengeance on Angel and to somehow "save the world" and bring forth the next step of evolution.
In 1935, Pearl, along with Nash was born to a human, who intentionally bred with a demon, believing her children to be the next step in evolution. In 1940, at the age of five, they were schooled regularly by their mother about their "greater purpose" and taught to uphold and live up to it the best way they could.
In 1953, she and Nash were present in Rome to find partners to procreate with. She had sex with a Black Widower demon before it attempted to eat her. This demon was in debt with Spike who suddenly appeared, dropped in and became an accidental hero, decapitating the demon and inadvertently rescuing Pearl, causing her to proclaim him as her hero while Nash had been knocked out. Spike lit up a cigarette and quickly left with Drusilla, his business finished. Pearl became fascinated with the vampire. 
In 1970, Pearl and Nash both followed their mother's plan and bred with demons themselves. All of their children were killed by monster-hunters however, among then Alasdair Coames. Their mother suggested to them that instead of breeding with demons, they breed with humans possessing strong magic, since not being able to blend in made their children vulnerable. 
Working for "Twilight"
Many years later, Pearl and Nash were approached by Twilight who told them of his plans to create a new, evolved universe, which along with his promise of bloodshed made them agree to work for him. Under his leadership, they killed Nadira's squad of slayers.
After Angel reneged on the Twilight affair, Pearl and Nash vowed revenge against him. After the loss of magic, their mother was no longer able to mystically prolong her life and asked her children to kill her. After they had massacred all the patrons of a bar, Whistler informs them that the world which doesn't know it's dead yet, needs to evolve. The twin accepted Whistler's proposition for the sake of bringing in the next stage of evolution and getting payback on their old boss, something their mother supported.
Working for Whistler
Attempting to find Angel, the three demons tracked him to Rupert Giles's former apartment- where Angel now lived with the slayer Faith Lehane as he attempted to complete Giles's unfinished business and find a way to bring the now-dead Giles back to life, but they only discovered Giles's aunts, Lavinia and Sophronia Fairweather - who Nash knew as both sisters had refused his marriage propositions on many occasions - as Angel was currently in Quor'toth with Faith, Willow Rosenberg and Connor. Informing the Giles family that he intended to complete the ascension that Buffy and Angel had interrupted as part of a plan to save the world by evolving it to the next stage, Whistler gave the aunts a card with an address on it and told them to tell Angel to meet him there on their 'anniversary'.
Later, the three demons concludes a pact with a very-living Eyghon the Sleepwalker to try and restore magic using accumulated magical artefacts to trigger a magic 'plague', with Whistler agreeing to give Eyghon control of Europe after magic has been restored, to rule as he sees fit. However Eyghon doesn't trust Pearl and Nash, conscious and afraid that they don't want share the power and would try to double-cross him.
When Alasdair's "cloaking device" for his magical items was shut down in an effort to help resurrect Giles, Whistler and his group quickly arrived on the scene. Pearl and Nash fiercely fought with Angel and Faith, intending to steal the items necessary. Eventually, when the three managed to steal the items, Whistler ordered the two of them to retreat since they had gotten what they wanted. Reluctantly, they obeyed and Whistler left again with them on his mission. 
Miraculously, Giles was successfully resurrected, but as an adult in a twelve-year-old body. With Giles' urging, Angel and the others headed out to stop Whistler's plan with the mutual agreement that not all of them would survive the fight. In the ensuing confrontation on a rooftop in Hackney, London, Angel desperately attempted to reason with Whistler, not wanting to fight his friend and benefactor, but his pleas fell on deaf ears; still believing that he was saving the world, Whistler unleashed a magical plague, mutating several people into monsters.
Although their plan was successful, Nash is killed by a revengeful Nadira, and a remorseful Whistler absorbed the plague ball in his own body to prevent it from spreading globally, charring his body to a fatal level, leaving Pearl alone.
Many months later, Pearl made a come-back, being the new muscle of the plague mutated pixie Corky Smallwood while remaining vengeful against Angel and Faith. After Angel follows some teenagers he spotted filling bottles with pure magick back to Corky's hideout. Pearl attacks Angel with a vengeance showcasing her improved powers such as emitting green electricity. While Pearl initially bests Angel, whom manages to blind Pearl with a bottle of magick, Corky reminds Pearl not to gloat. Pearl having been blinded flies off into the night warning Angel that this is not over.
Pearl demonstrate a blatant lack of empathy and disregard for human life, not for the same reasons that mainstream demon. Because of her half-demon statut, she feel humans emotion when losing her mother and her brother and had a certain human intelligence used for bad ways. This combination make her particulary dangerous and unpredictable. Indoctrinated by her mother, she consider herself like evolutionnist demon and feel superior to humans that she judge weaks and others demons excepted Whistler and her twin brother, that she judge archaic. In the 50's, she was somewhat naive and romantic, considering Spike like her hero.
Behind the Scenes
- Artist Rebekah Isaacs partly modeled Pearl's appearance on Karen O. In the Live Through This TPB artwork feature, the artist also says Pearl is modeled on Lady Gaga.
- Pearl and Nash are very similar to the children of the movie Village of the Damned.
- Pearl is also very similar to New Wave movement's singers like Hazel O'Connor or Dale Bozzio.
- Angel & Faith
- "Live Through This, Part One"
- "Live Through This, Part Two"
- "Live Through This, Part Three"
- "Live Through This, Part Four"
- "Family Reunion, Part One" (Only mentioned)
- "Family Reunion, Part Two"
- "Family Reunion, Part Three"
- "The Hero of His Own Story" (Also in flashbacks)
- "Death and Consequences, Part Three" (in flashbacks)
- "What You Want, Not What You Need, Part One"
- "What You Want, Not What You Need, Part Two"
- "What You Want, Not What You Need, Part Three"
- "What You Want, Not What You Need, Part Four"
- "What You Want, Not What You Need, Part Five"
- Spike: A Dark Place
- Angel & Faith