An explanation

You watched Arrival pretty much as soon as you were on the couch, and once the movie finished, you were hungry. You got up and made a sandwich, and decided to make a second one for Eileen whenever she woke up. You weren't really sure who this girl even was, but you knew damn well that she was gonna stay if you had any say in it.

Once you got out of the kitchen and made your way to the living room, Eileen was stirring. You brought the food to the coffee table, and started getting her up. She sensed that you knew not of why she was there, in a general sense, and after stretching and giving you a hug, began explaining.

Eileen explained that she was created by Kimiko Shinji, a Japanesse woman who wanted to make sex toys that she could feel when they were used, because no one in Japan wanted her. She accidentally created the most rapid system of reproduction the universe has ever seen, only taking two male ejaculations to create a full mature human, modeled after Marilyn Monroe at age 20. She soon found out that she could change existing humans by using the toys, and that the women the toys created could turn into different things intuitively, as innate as movement and thought.

"Wait, so you can shapeshift?" You ask.

"Yes," replied Eileen, "but I don't really like to. Not by my own will anyways."

You thought about this for a second. She said 'not by her own will' which means she was probably commanded by someone. But who?

"You, Dick." Says Eileen. "I'm controlled by your thoughts. When I was made, the first time you came into the toy, your genetics were imbedded into mine, permanently controlling me, binding me to you. The second was the catalyst for my creation."

"I suppose that makes you fatherly to me." Says Eileen, seemingly thinking out loud. "Or maybe, your my daddy she says as she mounts you, kissing you before looking up and panicking.