Thanks for your input @athelstone @seagreen @Janeshuff @kazg @Squidge @elle @Bellam
That 5 of you go towards YA / Children’s and the other 2 suggest SF / Fantasy tells me that the original name is still the one to use, although I will still make a minor tweak to it.
So, yes, it’s a literary-leaning novel about possession, with the MFC split.
To make an adult novel YA? Add -ina.