Alex Wesker's History
Origins
Alex was part of Ozwell E. Spencer's experiments to create a superior race that would inherit the Earth once he became a God. Similarly to the other "Wesker children", Alex was selected by the Umbrella Corporation for the project because of her superior DNA, having received a variant of the Progenitor virus. She and Albert Wesker were the only survivors out of the thirteen subjects, adapting to the virus and harnessing its abilities instead of being killed by it as happened to the other eleven Weskers; according to Spencer, Alex was always the brightest of them all. During her years in Umbrella, she had a close relationship to Albert and a friendly rivalry with William Birkin.
Initially, Alex worked alongside Spencer, helping him further his ambitions to become a God; however, she ultimately came to despise him and decide it was foolish to pander to his ideals. While pretending to be on his side, assuring him that all experiments were going smoothly, she drained Spencer of resources and personnel, using them to develop her own goals, unbeknown to him. As soon as she decided she didn't need him anymore, she discarded him — shunning his last, best hope at immortality and leaving him to die of old age.
At some point, Alex decided she should become an immortal god.
Ruler of Zabytij
Alex arrived at Zabytij Island in 2000, proceeding to modernize it and resurrect the local economy through industry and mining, which made her an almost godlike savior to the eyes of the population. Secretly, she set up research facilities both on the surface and underground, preparing to use the island to further her research. Sometime after the events of Resident Evil 5, Alex heard of Albert's death and she sent a team to Umbrella Africa Research Center in order to collect his final creation, the Uroboros virus which she wanted to use its power later on. On 19 July 2000, Alex arrived on the remote formerly Soviet Union-affiliated Sushestvovanie Island with a large team of researchers led by Stuart.
She then brainwahed the inhabitants and her own workers to work for her, to think highly of her as well, calling her "Lady Alex" and following her without question and due to their loyalty Alex used the employees hired to work in the mines as her personal test subjects to develop the t-Phobos Virus, turning most of them into B.O.W.s.
Research On Immortality
After most of Umbrella have fallen, Alex continued her work for Spencer, being the last remaining child at his side. The brightest of them all, in Spencer's view and words, "Alex excels at absorbing the abilities of others." Alex was tasked with conducting experiments for Spencer on a research facility on Sonido de Tortuga Island, where she would study Umbrella's viruses in order to elucidate the latent ability of immortality from the Progenitor Virus for Spencer. Alex failed to develop the virus, instead siphoning out resources for personal projects but reported progress to Spencer in order to keep her supply of resources. Then, in 2006, she abandoned Spencer and the island taking all of the results.
Albert's Legacy
When the BSAA confirmed the death of Albert in a recent mission in Africa, Alex immediately ordered her research team, led by Stuart, to head to the former Umbrella Africa Laboratory to retrieve a sample of the Uroboros Virus. Alex was one of the few people who actually knew about the laboratory's existence and location, after Spencer's assassination at the hands of Albert, she was able to figure out that Albert had discovered the location of the laboratory and would use it to reach his goals.
Fear Experiments
Alex realized that the illness she had was weakening her body from the inside. Knowing that she wouldn't be able to escape her imminent death, and that biological immortality could not be obtained by viruses or human experiments, Alex turned to her last resort; transferring a digitized copy of her human consciousness into another host. To that end, she affiliated herself with senior Terra Save member Neil Fisher. She enlisted his help to procure a human host with a special mental condition in exchange of a Uroboros Virus sample in return.
In 2011, Alex sent her private militia to capture Claire Redfield, Moira Burton, and other TerraSave members to Sushestvovanie Island to be used as test subjects for T-Phobos. Amidst the confusion, Alex sent Neil to abduct Natalia Korda, one of her prisoners on the island, to commence her "rebirth ceremony."
When Claire and Moira discovered Neil Fisher's betrayal in TerraSave who was responsible for the attack of their headquarters, Alex instead betrayed Neil by injecting him with Uroboros virus. She also brought up about the Terragrigia Panic seven years ago and Neil was one of Morgan Lansdale's puppets as she left him to mutate. Despite being injected Neil has been accepted by Uroboros and transformed into a Tyrant-like monster. After Neil was defeated, Alex prepared to transfer the part of her own consciousness into Natalia. Later, she was confronted by Claire and Moira, during which she revealed her true intentions before shooting herself in the head. However, T-Phobos virus inside her began to mutate and her death caused the whole tower to self-destruct.
Reborn From Fear
6 months later, Alex barely survives the suicide attempt and her body turned into a monstrous hunchback. She uses a green robe and a mask to hide her hideous body and Alex begins to hate Natalia Korda and plans on killing her due to not mutating like Alex. Natalia and Alex finally meet face to face when she wanders into a candle-filled chamber with Barry Burton, father of Moira Burton. Laughing at Natalia, Alex claims to have killed Moira six months ago, infuriating Barry who is also surprised to hear that Alex is a Wesker Child and a sister of Albert Wesker. Alex summons a group of Revenant to kill Natalia and Barry, but they evade the creatures and retreat to the bowels of the ruined facility.
Alex manages to ambush them at the abandoned town as she knocks Barry onto the cliff and attempts to kill Natalia by choking her. Alex becomes angered to see Natalia retains her human form while hers is mutated. As Natalia open her eyes, Alex lets go and making her scream in terror at the glance of her. When they confront her at her secret underground cave, she takes in a vial dose of Uroboros virus in a last ditch attempt to destroy Natalia. Alex screams about her wish to "transcend" and transforms into Monster Alex. A duel ensued between her and Barry as he manages to bring her down temporarily, however, she manages to knock Barry down, making her way on Natalia to exact her revenge, only to be interrupted by Moira.
As the trio escapes, the Uroboros consumed her further as she pursues the trio. Claire Redfield then shows up with a helicopter and urges the survivors to get on board. Claire joins Barry in their attempt to defeat the monstrosity. As Barry distracts Alex through the mines, Claire manages to shoot her exposed core with an RPG-7, killing her.
Life Inside Natalia's Body
Two years later, Alex's copied consciousness dwells inside Natalia's body, unnoticed by everyone. Natalia is seen reading a work of Franz Kafka, among other articles about Bioterrorism. Realizing her experiment on immortality was a success, Natalia/Alex grins a malicious smile.
