Eveline

Eveline was a girl engineered by an unidentified company (possibly the Rival company) as one in a series of human-based bio-weapon products. Capable of manipulating people without using a special serum, she was created for the purpose of infiltrating political or military organizations.

Biography
In 2014, Eveline was entrusted in the care of Mia Winters as a babysitter. Following an explosion on a ship they were on, the two were recovered by the Baker family in southern Louisiana. There, Eveline quickly gained control of the family. Without access to medication to keep Eveline healthy, she began to rapidly age twenty-five times faster than the normal human growth rate, and quickly gained the appearance of an elderly woman confined in a wheelchair. With her mind deteriorating, her control of the Bakers became more aggressive and they began murdering a number of people in the area on her behalf.

Resident Evil 7: Beginning Hour
Although Eveline isn't seen, she has still contaminated the Baker Family and Jack Baker stalks the protagonist. Depending on the true ending, Jack Baker isn't seen, but if the true ending doesn't happen, Jack will appear and punch the protagonist unconscious.

Resident Evil 7: KITCHEN
Although Eveline isn't seen, her influence still stalks the Baker Family. In the demo, the player character, Clancy Javis, is bound at the wrists in a kitchen. Before him, is Peter Walken, who is initially unconscious. When he comes to, he grabs a rusted machete and attempts to release Clancy. He is interrupted by a manipulated Mia Winters, who stabs him from behind. She then turns to Clancy, licking her knife before stabbing him in the leg. Pete then tackles her out of the room in a brief struggle, after several moments his decapitated head rolls in front of Clancy as her heavy breathing can be heard behind him. Mia then places her hands on Clancy's face and pulls them away before her face appears and she holds her knife at him.

Resident Evil 7: Biohazard
Ethan Winters arrives at the Baker Family's residence in search of his missing and presumed dead wife, Mia Winters, he will find out that she will be normal, but turn in an instant into a monstrosity. The first interaction of this is when Mia and Ethan are attempting to leave the plantation, but she ends up turning, attempts to stab Ethan with a knife. After realizing what she's done, Mia screams that she can feel "her" clawing her way back inside her. Mia starts to bang her head on a wall in an attempt to kill herself. While it momentarily stops her, Mia then floats back up straight, with her body turning monstrous again. She grabs Ethan, and throws him through a wall, then grabs a piece of rebar in the wall. A fight between the couple ensue with Mia telling Ethan that she's dead and that she can't leave the plantation. After a brief moment, Ethan ends the fight by slashing Mia in the throat. She falls over in a pool of her own blood. After a phone call from Zoe Baker, Ethan finds that Mia is no longer on the ground. He searches for her, and finds her stalking around the house. After walking back out into the hallway, a seemingly calm Mia tries to talk to Ethan, before turning monstrous again, and slamming him against the wall saying, "you shouldn't have done that." Afterwards, Mia stabs Ethan with a screwdriver, and scuttles off. As Ethan tries to free his hand from the screwdriver, Mia comes back around clutching a chainsaw. As Ethan finally frees his hand, he blocks the chainsaw with his forearm, which Mia promptly cuts off, laughing creepily.

A still contaminated Mia slices her way through a wall, prompting Ethan to start shooting her. Eventually shooting Mia enough times, Mia says that she loves Ethan and falls over. After the battle, Jack Baker appears behind Ethan and says, "Welcome to the family, son." and punches Ethan next to Mia. Jack then, slings Mia over his shoulder and drags Ethan to the family dinner table.

Ethan wakes up to the monstrous Baker family, and an elderly lady slumped in a wheelchair next to them. The dinner table is filled with multiple nasty offerings, as evidenced by the cannibalistic nature of the Bakers. Throughout Resident Evil 7, Ethan has multiple run-ins with the elderly lady on multiple parts of the property. The Baker family also starts to speak of young "Evie" who doesn't make any appearances.

Eventually, Ethan starts to hear a giggling girl. After picking up a piece for the "serum", Ethan catches a glance of the young girl for the very first time before she runs off. After Ethan starts to follow clues to each location, he will see the elderly lady, sitting there quietly. There was one instance, where she was even awake and staring at him as he walked around.

He begins to learn the mystery of young "Evie". Her name is Eveline, and she had a way of manipulating people's minds. Eventually, she started to interact with Ethan, appearing in one place, or another.

If Ethan decides to cure Mia, she will take over as the playable character while she searches for Ethan in the beached tanker. Mia will figure out the whole backstory, and recover her memories through a videotape taken before the events of KITCHEN, and Beginning Hour. Eveline is a new BOW with the ability to forcibly take over people's minds. In doing so, she will add them to her "family" as she calls it. However, during the time on the tanker, Mia and her CIA Director will end up fighting for survival aboard it while Eveline "plays" with Mia. Eveline then asks Mia is she will be her "mommy", in which Mia frantically replies yes in order to stop the play-time with Eveline. However, Eveline won't let up. Mia and the CIA Director reveal that Eveline has been off her meds and that is causing her mind to deteriorate. Eveline eventually kills the Director for calling her a "bitch", and asks Mia if she's ready to be her mommy. Mia says that she's not her mommy, that causing Eveline to reject her and contaminate her.

Eveline continues to call Mia, "Mommy" and wants to know if Mia is ready to be a family. Rejecting her outright, Mia starts looking for Ethan again while Eveline continues to torment Mia. After finding Ethan, Eveline states that she can make Ethan love her, because he doesn't. Mia pleads with Eveline to not hurt Ethan to which she childishly replies that she would never hurt him.

Jack, Ethan, and Zoe will be seen while Mia is exploring the tanker in a dreamlike state. Jack explains that he picked up Eveline, and Mia by the abandoned tanker, not knowing who he picked up. A saddened Jack then tells Ethan that he didn't want to hurt Ethan, but he couldn't help it. He continued to explain that Eveline forces her way into the head of his family, changing them against their will. Offering a very real explanation, Eveline just wanted a family. However, he wants Ethan to stop Eveline and free his family. The dreamlike state ends while Jack and Zoe disappear, no longer controlled by Eveline.

Freeing Ethan from the molded binds, Eveline hands Ethan a vile and states that he needs to find her and stop this. She pushes Ethan and closes the door with the Eveline hallucination behind her, causing her to turn contaminated again. Ethan makes his way out back into the main house of the Baker family, where he ends up interacting with Eveline, who's burrowing herself into Ethan's mind.

Ethan then sees a picture with the number E-001 on it and a picture of and old woman on the front, signifying that she is E-001. This picture can also be interacted with at the beginning of the game, however E-001 means nothing at this point. Working his way back up to the attic, the hallucination begins to show him flashbacks of Mia's attacks against Ethan. Piecing everything together, he realizes that her monstrous outbursts is because Eveline wants her to kill him for not being her "daddy." During this sequence, he works his way up to the attic, and gives the childish Eveline the serum.

He then realizes that Eveline is in fact the old lady, as she begins crying tears of black, asking why everyone hates her since she just wanted a family. However, as she's melting, she says, "Damn you. Damn you all to hell." In which case, her molded powers take over the entire attic, and rips Ethan from the attic and into the yard below. Mercenary helicopters arrive in the skies above as a fantastical battle between Ethan and the absolutely out-of-control powers of Eveline take over. She screams throughout the battle that she wanted a family, while continuing to pummel Ethan, who had the wind knocked out of him. Eventually, using the Wesker-01 gun, he deals enough damage to finally cause Eveline to dry up, ending her control over others; and kills her.

Further Notes

 * Eveline always referred to Mia as "Mommy" considering how this B.O.W. was said to get attached to it's handler who should assume the relative role and in this case the mother, even when telling Mia to attack people she would call her "Mommy" or "Mother"
 * In a flashback scene, shown by Eveline's mind manipulation to Ethan; it shows that she commanded Mia to saw off his hand when she thought he doesn't want to be her daddy.
 * Although unknown to the player at the time, there is a picture with the number E-001 and a picture of the elderly Eveline can be seen at the beginning of the game. It's unknown who took the picture and wrote the type on the type, although Mia could've been the one as she knew that info and was the only one who survived the tanker attack.
 * Eveline ages extremely quickly due to not having the medicine to keep her powers in check. Because of this, her mind deteriorated much more quickly.
 * The promotional poster of Resident Evil 7: Biohazard contains all the antagonists: the Baker family and Eveline. From a glance, however, it would seem that Eveline is just a stereotypical elderly matriarch from the horror genre.
 * Eveline's influence was seen throughout all the demos and full game playthrough, althought she wasn't interacted with in full until the last third of Resident Evil 7: Biohazard.