Being a lesbian doesn't make anyone less susceptible to The Dark Side.
Lesbian women represent a large group (even if only 1% of women were lesbians, it would still mean 35 million lesbians). Women suffering from dangerous psychosis are also a large group (if 1% of women were dangerously psychotic, it would account for 35 millions of them). Statistically, some degree of overlap between two sufficiently large groups which are not mutually exclusive is virtually guaranteed. So statistics dictate there would be at least a few psychotic lesbians running around.
Alice is the Only Sane Man in a cast of psychotic straight people.
The villains are a straight guy who thinks Girl-on-Girl Is Hot and a rabid Yuri Fan that creep out Alice with their unwelcome propositions.
Alice is revealed to be a lesbian, and nobody dares look at her, for fear they'll be hurt.
Zig Zagged: Alice is actually trying to escape from Emperor Evulz and is constructing a plan with Stephanie, but before that can happen, she breaks from the stress and goes truly insane, then Stephanie reveals that she has been working for Master of Destruction all along..
Lesbians are just as sane or insane as the rest of the cast.
There are no gay characters in the cast.
"True lesbians are very efficient as scary opponents since women fear being raped by them and men just can't seduce them."
Alice is in an anime/videogame/name-your-medium-here that covers a lot of fetishes.
Lampshaded: "My dear Stephanie, you don't seem to understand. I want you and no is not an answer. Simple as that."