maybe drew is bi and sterling will just seduce&fuck her and share everyone,then it becomes a poly relationhip
I honestly believe he is Bi. Hunter said he openly was peeved with him for showing no interest in women despite however much he was desired by Hunter to be the one to carry his legacy. It was only when Keira (Lucia's mom) was introduced to him that he finally showed interest in the fairer sex and thus he managed to coax Drew into banging her (as well as her mom... i think, i cant recall if he actually did the mom or if it was just Hunter).
As for if Drew still has the "man bits" we dont know unless WWG has said something on the matter. Its not confirmed one way or another in the story, its beyond question Drew was once a dude but i dont know if hes fully transitioned or not. I do think its already been confirmed Drew is planned to be an antagonist much like Hunter but that could still be very much the case fully transitioned (Brenna and Eva are already into women, Catherine has been pondering it after having to pretend it was her BFF she was peeping on and not Sterling, Mallory is in recent plotline not Bi but Eva has every intention of changing that fact, Kumiko is basically a sex worker so doubt anything is off the cards with her, Lucia is doing just about anything to get herself off these days etc).
I think Sterling will eventually fuck her - the whole premise is Sterling is turning the tables on NTR wannabes, him fucking his "aunt" aka Hunters biggest trump card will be the ultimate middle finger to the old bastard (regardless of man bits intact or not... its a meme really how there is a 100% rate of Trans characters in porn games not ever fully transitioning. WWG will perhaps have one eye on Drew catering to those fans as potential supporters for the game with the characters inclusion as well)
