In Eli Roth's movie "Knock Knock" when Bell and Genesis are loading Louis' dead body into the van, who are they talking about when they say "Ronnie can make anything disappear"? I have searched but can't find anything on this and it is the only time in the movie this name is mentioned.
It's a shame this movie is as bad as it is, or this question may have attracted a more authoritative answer. Frankly, I feel like this was a line thrown in the movie deliberately to give the two girls and their shenanigans the appearance of depth that just simply wasn't backed up by the rest of the movie. Instead, it just comes off as an annoying non sequitur for lack of any additional references in that direction.
I wish there was more back story to these girls but if there is it would probably be introduced in an even lower budget prequel / sequel film.
Eli Roth, I believe, is an amazing movie maker that wants his audience to focus on the horror of this film. My theory is he purposely paints a dull picture void of any true depth to allow the horror and terror to stand out even more than what it really does.
As for the girls.... It's not their first rodeo. My guess is they've been traumatized in the past, to the point where they believe it's their purpose in life to dispatch the "dirty old men" that once preyed upon then.
Genesis, is an interesting name, but likely its not her given. She, of course, appears the be the mastermind. She has probably judged "guilty" men in the past and picked Bell up along the way.
Bell is still fairly new to her new judiciary roll. Genesis must feels as though she was the first to be "created" for this roll as judge, jury and executioner and must pass her twisted ways on to other young ladies in order to cleanse the world of this evil filth.
So they show up to a man's house and test his "decency". If the man passes then they move on. But Genesis is bitter and she has yet to find a man that is "good". Bell, on the other hand, still has some hope. You can see Bell throughout the film question what they are doing to Evan. Maybe they've gone a little to far and Evan really is a "good" guy forced into a "bad" situation.
As for Ronnie, he/she (maybe a Veronica adding more "judges of character" for future films) helps in adding depth to their habitual purging of preditors. They've done this enough times to have "a guy" that cleans up their mess once a verdict has been handed out.
So....long story short, Lefem Nakita style, Ronnie (or Veronica) is a Cleaner... plain and simple.