Whip/Story

Past
According to the 2001 novel written by Akihiko Ureshino, Whip is a clone of the real Seirah; Seirah was K's biological older sister who died after being abducted by NESTS. Ureshino comments that he wrote this origin story for her because the developers didn't want to clarify anything about her to him. Until this was written, Seirah is only shown briefly as a child in K's memories, imploring her younger brother (K') to remain strong until they meet again.

Regardless of whether she is a clone or not, she is called Seirah by people who knew her in NESTS. She also responds to the nicknames Sally or Sarah. Due to NESTS experimentation on her body, she's able to manipulate her specialized whip with ease. She befriended Krizalid under the assumption that he was her brother before she escaped from the cartel. She used Sally as a codename to join the military. She is eventually assigned to Heidern's mercenary unit under her current name, Whip.

The King of Fighters '99
Heidern informs Ralf Jones, Clark Still, Leona Heidern, and Whip

Axe Platoon

A few hours after the tournament's conclusion, Whip returned back to the area where the final battle took place and found Krizalid, still barely alive from the crash. She asks Krizalid if he remembers his father's face, to which he discovers that he cannot remember. Whip reveals to him the reason why he couldn't is because he was not her brother; K' was. Krizalid would shortly die realizing that he was K' clone. His corpse was later taken into custody by the Ikari mercenaries, with Whip crying silently.

The King of Fighters 2000
After learning a startling but undisclosed revelation from Zero, she joins K' and his objective to destroy NESTS. After NESTS's downfall, she returns to her duties under Heidern's command.

The King of Fighters 2001
They spend the remainder of the year hunting down NESTS's bases around the globe. Though they have stumped some of the syndicate's plans, none of the bases were the main headquarters they were hoping for. K' and company enter the 2001 tournament with Lin, who tracked their movements in his personal hunt for Ron. Once his team makes it to the finals, they are lifted into a spaceship and are confronted by the real Zero. He reveals to the frustrated K' that they are on their way to the syndicate's main headquarters and will meet the real leader to NESTS. Once they reach the satellite, they meet Nests, Misty, and Igniz.

Although Nests requests their neutral cooperation, he is quickly killed by Igniz. Shortly afterwards, Igniz reveals to K' and his team that K', Kula, Krizalid, and K9999 that they were merely modified humans (or clones) purely created for Igniz's personal entertainment (i.e. to become a new god). K' faces the villain and with some assistance from his team defeats him, which motivates Igniz to kamikaze the satellite to Earth. It harmlessly falls in the ocean (apparently thanks to Ron) with most of its passengers safe. Emerging from the wreck, K' forms an alliance with Kula and Diana. Both of them want to make their own future and make up for the time lost in their lives.

The King of Fighters 2003
In 2003, Chin Gentsai visits K' and Maxima and requests that they enter the tournament. Chin, feeling a dark wave of energy around KOF that year, wants them to investigate it in his place. K' and company locate and face Mukai. The K' Team defeats him, but K' was bothered by Mukai's taunts about regaining his memories, as well as reaching his true potential.

The King of Fighters XI
During the KOF XI tournament, she serves as backup for the Ikari team and asked Kula Diamond to enter the tournament with K' and Maxima. After Magaki's death, his body was collected by Heidern and the Ikari Warriors. The next day during a meeting, two members of Those From the Past boarded on Heidern's main ship and took Magaki's dead body away, their farewell gift being an explosion on one of the fleet's vessels.

The King of Fighters XIII
After the tournament's climax, she loses consciousness and sleeps for several days. Her teammates were worried for her and stay beside her until she awakens. Comforted by their concerns, she laughs for the first time in the series.

The King of Fighters XIV
36 hours after the tournaments conclusion, Heidern confirms that there are bodies that were resurrected and has already commenced a 24 hour surveillance.