Wow, I just read that entire thing. While the beginning with the security explanation was believable, (I don't know if it works that way but it sounded true to me) the rest of it was not. "Allison" even spelled her bosses name wrong (Katie) and Russ didn't catch it.
It is seriously hard to imagine a person that delusional, who thinks a conversation like that could ever happen and be real. And it gets more and more obvious, as Allison quickly responds to everything within minutes despite her assertions of being so busy, and loses her professional voice, and then we hear about Russell Brand and his sex addiction and how Katy was into it and liked uncut men, and liked to pet his chest hair (of which he has none). Russ just doesn't go...."hmmmm" this isn't a normal conversation between acquaintances, much less complete strangers, one of whom is an employee? A couple times he asks for reassurance, so he is suspicious, but is very easily put off as he wants to believe it so bad. "It's real, right?" Yeah, it's real. Ok. He HAD to have known it wasn't real but was willing to let his desire overcome his suspicions.
And, he whined and complained, as one would expect. Not that it is in any way believable but if it was, the "I don't want to share a room or eat dinner with others" and does "Katy want me in bed" stuff...just wow.
He has focused only on himself. He never asks a single question about Allison, or Katy, unless it relates to him. I mean, if I was talking to a pop star's assistant, I might have a few questions about how she came to do it, what the job was like. But he's only interested in himself.
He probably hates his brother now for being suspicious more than anybody else.
What was the last question about his parents address supposed to be?