Bel and Genesis

Bel and Genesis are the antagonists of the 2015 horror-comedy Knock-Knock by Eli Roth.

Biography
Bel and Genesis arrive at the home of family man Evan Webber, whose wife and children are currently out of town while he works from home. They tell him that they're stranded on their way to a friend's house and ask if they can use his phone. Evan invites them inside and they chat while waiting for a taxi to arrive. The girls decide they don't want to leave and use Evan's bathroom. Evan demands that they get out, but the girls aggressively come onto him and he ultimately gives in, having a threesome with the girls both in the bathroom and in his bedroom.

The next morning, Evan awakens to see that Bel and Genesis have made themselves at home. He demands that they leave now or he'll call the police, but they tell him that they're only 15 and thus could get him imprisoned for statutory rape. Evan is then forced to become the girls' plaything, enduring an increasing amount of humiliation over the course of the film as his home and all of his possessions are ruined, his wife's business partner is killed and a video of Evan being forced to have sex with Bel wearing his daughter's school uniform is uploaded to his Facebook page.

In the end, Bel and Genesis leave Evan buried up to his neck in his backyard and make their way onto their next victim.

Personalities
Bel and Genesis are both extremely psychotic, not thinking twice about the things they do and enjoying every bit of pain they inflict. They have a warped sense of justice, believing that married men deserve to die if they cheat and that they should be the judge, jury and executioners. Genesis is most likely the brains of the two, as she's the one who usually explains their plans and motivations. Bel's psychosis is especially prominent, as she mentions being molested by her step-father.