Changed into my best friend’s breeding slut

In this world, futas have this unique ability with their cum. An ability that scientists can only note the side effects of and not why the cum has this ability. To put it simply, if you get fucked by a futa and they come in you. Boom! Done! Your life is changed forever. The cum alters the mind, making the person who ingested the cum find the taste of the cum to be extraordinary and they must need more. They will become the sexual or harem slut of the futa who came in them, if the futa or the person who takes the cum wants it or not. It is simply what will happen. They will decide their new life to making sure the mistress gets as much pleasure and is in as much comfort as possible.

The body of the cum taker will change to. How? Scientists don't know but it seems to change them to meet the futas ideals of peak body and sexuality. If the futa wants a petite horny slut who has constantly tight holes, the cum giver will change into that, even if it means changing genders to do so. This can lead to a harem of the same type of harem slut or of different types depending on how much the preferences of the futa change.