Here let me fan-fic some shit for you:
Not-Umbrella (we'll just call them "Poncho") tries to create a bioweapon capable of both being able to hide in plain sight as well as manipulating the target populace. They choose to model the "virus" after a child, that could be paired with a false family unit at the behest of whichever rebel nation purchases it. But to do that successfully, they had to condition the "child" desire and require a mother, father, and even siblings just like a real child would.
What they didn't expect, because let's be honest those fuckers are coked up 24/7, that the child would end up acting like a curious George and steal their bootleg tapes recorded with ABC network's long-defunct TGIF primetime block. On sub-level 1 of the ship, there's VHS titled "EV-001 watches a very special Step-by-Step Xmas." It, of course, shows Evie taping herself watch a tape of said special, and becoming psychologically warped even further.
Mia catches her while she's going through the credits, and Evie asks Mia why Cody appeared at the start but just sort of disappeared by the dinner scene at the end. Mia tells her "Stop calling me mommy do I look haggard and used up" and then proceeds to punch the VHS player like Chris Redfield because there's like a training video they show everyone who joins the BOW field and- anyways, this pisses Evie right off and she starts fucking everything in the ship up. And she wants Cody, eventually realizing that Jack is too old but this guy Ethan Mia keeps apologizing to in her sleep...
Also Ethan "accidentally" set the neighbor's cat on fire as a kid and he's been kinda off ever since.