It just occurred to me the downside if of this sub-genre: If the whole vampire/zombie/horror thing just leaves you cold then there's no g/g soup for you here - and none of those customers' $$$ for the producer.
Obviously it's a bet producers make that the number of fans attracted by it - including some who may not be regular g/g consumers - will outnumber those who are not - including some who are regular g/g consumers.
I wouldn't bet against them.
Plus, who am I to talk about niche preferences, the author of a lez taboo, reluctance and non-consent thread that strikes many as even more exclusive.
Regarding this film and that thread, although the vampire/horror thing lends itself to non-consent (and it's evil non-twin coercion), the OP of that thread also specifies a particular motivation: a girl or woman experiencing psychological turmoil from doing something she feels is "wrong" or "not done" by good girls like herself - engaging in lesbian sex acts. That excludes drugs, mystical spells, bitten by a vamp, etc., which leave no room for psychological turmoil because they take over or suppress the mind.