Well, thank you first of all. I have had other ideas, but I wanted to wait until I've heard what people think of this one. Just spewing out all of my ideas seems pointless to me. I admitted to a major weakness for the sake of getting better advice. >This has overtones of sex involving underage characters. I'm not saying to not do this. I am saying that you should have a good idea of how your audience will react to this.
lol that's the whole point so I don't care. I definitely wont put in an actual sex scene if I do get around to it, because it's not meant to be smut. I also don't plan on publishing it or making any money off of it. I'll just post it somewhere online under an alias and ask people for critique.
Addition: It would probably also make more sense if the girls were introduced as totally normal and the mc gets his ability after some thing, whatever, happens to him.
What POV is the story seen from?
If it's the guy, how'd the reader know they're aliens disgusted as cute girls if he can see right through them?
Probably the third person. It's kind of stupid, but maybe the main character meets the girls and they look totally normal to him, but then one day he accidentally drinks from one of their water bottles instead of his own, which makes him really sick, but after that he can see their true selves. Maybe as they're visiting him while he is sick, he's like in some kind of a transitional phase where they sometimes look human to him, and sometimes don't, which allows him to connect the dots. Or maybe he finds out through a fever dream somehow. I don't know. How dumb does that sound? The visitations would require the main character to already have some kind of connection with the five(or three, doesn't matter) monsters. Maybe that could be done through a mutual friend.