What happens with Candie?
My wife made a trenchant observation. If Candie is so frustrating to the Mitchums, why don't they ever ask the other girls to do anything? A nice subtle "battle of the sexes" thing going on: if you identify with the men, Candie is just a slow, dumb pretty girl who can't do anything right; but from Candie's side, the men are stupid for continuing to ask her to do things she doesn't want to, so she deliberately makes them suffer through it. The men enjoy their (false) feeling of superiority while the woman enjoys getting one over on them.
The scene with the fly was a cliche stretched to the breaking point: utterly predictable and unbearably long, it seemed to be signalling, "You know where this is going..."
As to who she "really" is or what will happen, I cannot guess.
I'm certain in the very first episode, Duncan Todd says something like "have you found the girl, she's good enough", or something like that.
I thought at the time they were referring to a girl who has been chosen to do something important. I wonder if Candie is the one. Ie she's a plant.
It's actually way more concise, he just says "tell her she has the job", so it's a female, but we don't really know if it's a woman or a girl, nor if the task is meaningful. The only thing we learn from that conversation is apparently that the job he's giving to this girl/woman is related to something that someone terrible is forcing him to do (as Roger, the assistant, asks Duncan Todd "why do you let him make you do these things"). I always thought it was referred to Mr. C and it's basically confirmed as we learned in part 9 that Mr. C gave Todd the assignment of killing Dougie. So I thought (and I still think) that the "her" in question was one of the various sub-contractors hitmen Todd has hired, namely the first one, Lorraine, the woman we see screaming nervously on the phone with the gun men she's hired, then texting to the box in Buenos Aires, then getting stabbed to death by Ike the Spike for her failure. But I won't rule out your theory, I'm intrigued by it.