Arlecchino, formerly known as Peruere, was an orphan who grew up in the House of the Hearth, a Fatui orphanage. This orphanage was a harsh place, where the children were forced to compete against one another in lethal contests to attain the title of "King." Arlecchino was compelled to battle her friend Clervie, the daughter of the director known as "Mother" or Crucabena, resulting in Clervie's death. Following this, Arlecchino confronted and killed Crucabena, the former Knave, after Crucabena had offered to instruct her on how to become the "King." The Tsaritsa, impressed by Arlecchino's actions, granted her a pardon and appointed her as the new Knave, thereby taking control of the House of the Hearth. Arlecchino possesses a distinctive ability to utilize blood magic, which is regarded as both a curse and a blessing, linked to the ancient Balemoon Bloodfire. Known as "The Knave," Arlecchino is recognized for her strategic and calculated demeanor. She holds a prominent position within the Fatui Harbingers, serving as the director of the House of the Hearth orphanage. Although she portrays herself as a strict and sometimes ruthless individual, especially towards those outside the orphanage, she also demonstrates a caring and protective nature towards the children in her charge. Arlecchino is a strategist, consistently thinking several steps ahead and weighing the consequences of her decisions. She expects discipline and loyalty from her subordinates, yet she is also open to granting second chances and adopting a more lenient stance than her predecessor. Despite her tough exterior, Arlecchino has a profound affection for the children at the House of the Hearth and is fiercely protective of them. Her motivations and actions often remain ambiguous, leading to speculation regarding whether she is genuinely malevolent or if there exists a more complex rationale behind her behavior. The children of the House of the Hearth refer to her as "Father," underscoring her role as a parental figure despite her status as a Harbinger. While some may view her as deranged, her actions and demeanor are typically depicted as cold, calculating, and at times ruthless, but not necessarily insane. Arlecchino is a tall, slender woman with pale skin and striking features. Her most distinctive trait is her eyes, which possess a black iris and red pupils shaped like an 'X'. She has long, asymmetric white hair with black streaks, styled to the right side of her head. In her Harbinger uniform, she dons a double-breasted white overcoat featuring grey lapels and a black fur collar, along with a Snezhnayan Pyro Vision located on the back of her neck. Additionally, she wears a sleek outfit consisting of gray and white suit and pants.

Lyney and Lynette lost their parents, becoming orphans. They wandered the streets with their older brother, Lucien, who looked after them. One day, a nobleman observed Lyney, Lynette, and Lucien as they practiced their magic on the street. Captivated by their talent, he took the twins in. Initially, they were thrilled to finally have a home. They transitioned from being orphans begging on the streets to living in nobility within moments; however, this joy was fleeting. It soon became clear that their adoption was merely for the purpose of being paraded like a trophy at banquets and parties, where they were compelled to perform. Arlecchino had been pursuing the man for some time and successfully rescued Lynette along with several other young girls who were confined in the basement. Fortunately, they were all still alive. This incident left both twins deeply traumatized. It rendered Lyney co-dependent on Lynette, making it difficult for him to handle separation. Being unexpectedly separated from Lynette, or for a prolonged duration, induces severe anxiety in him. After their rescue, Lyney, Lynette, and Lucien were taken in by the House of Hearth, an orphanage overseen by the Fatui Harbinger Arlecchino, known by the codename "Knave". To the children residing in the House of Hearth, she is simply referred to as "Father". Being adopted into the House of Hearth enabled the twins and Lucien to relocate to the Hotel Bouffes d'ete, alongside other orphans who had faced similar circumstances. However, they were not accompanied by Lucien, who became increasingly absent due to Arlecchino's demands.