For the relationship with the MC it is currently much more important whether her and the MC's attitudes (evil or good) are aligned and whether you make decisions with the MC (especially on the Dom path (K5+)) that are aligned with Olivia's attitude.
And the way the evil/good values is checked is often a bit weird, so it's rarely "which one is highest?" but e.g. "is
sisgood
above 6?" or "is
sisevil
above 15?" So you can make almost exclusively evil choices but sometimes the game will still assume that Olivia is a goody two-shoes if you've made one or two choices in that direction.
If you play Kane as dominant, you'll see fewer scenes where Olivia has the
opportunity to make moral choices. So you can play her as almost entirely evil, but if Kane is on the dom track, you'll still occasionally miss "evil" events with her and be shunted onto the good (or at least morally neutral) track because she hasn't accumulated enough
sisevil
points.
Most notably, the game will occasionally check one particular decision regarding the other brother, Seth, instead, ignoring the good/evil score entirely (although that decision also gives a major points swing).