So only Hecate powers effect Ms.Collins but not Selene powers?
Selene powers effect Ms.Collins too. But her powers work much more effectively on those in the dreams we've been in, Selene said so at the beginning of the game. It also depends on the person whether he will resist the powers or not, after all, it does not work as straightforwardly as Hecate's powers.
Alright, I tried two different play throughs with and without Hecate's powers. And without using her powers, I try to see if the MC doesn't be submissive or a sex slave to Ms.Collins but couldn't figure it out how.
So this is my theory on one of the next updates.
The MC will be able to go into Ms.Collins dream and somehow change her ways while using Selene's powers but without using Hecate's powers.