if you actually believe she's there to help Hunter at all which I don't think that's the case I think she's there because she actually wants Sterling if you’ve seen the ending of 10 and you've heard what Sterling's own thoughts on the subject were
What of the ending of chapter 10? I trust nothing but first hand information. For all we know, that "affair" between David and Drew was a set up to drive David and Ophelia apart to get David out of the picture so he could come back. To make a bolder claim, has it ever been established how David exactly died? Food for thought, I'd say. As for Sterling's own thoughts on the subject, Sterling can only work with the information at hand (which means even less information we have, since we have access to the non-canon endings), so he doesn't give any hidden insights. Sterling THINKS Drew is gay because of that e-mail, even though Hunter has said many times Drew is worse than he is.
it's a little bit obvious that Drew is trying to draw Sterling's attention with the clothing she's wearing
Of everyone in the house, Sterling is the only person Drew hasn't really interacted with. Everyone had some time alone with Drew, except for Sterling. And you think Drew is trying to get his attention that way? If Drew had their sights set on Sterling, they'd be all over him. Instead, they're charming everyone EXCEPT Sterling, possibly because they didn't seen them as a threat because they misread him. Now that they know Sterling is straight and VERY interested in women, they won't take him as lightly.