He might be trying to tell you something

Kill it before it breeds.

I don't think there's anything particularly strange about his sexual interest in MLP, everybody has some kind of kink (or even if someone doesn't appear to, surely they just aren't looking hard enough), but you might want to talk to him about privacy unless you were really making an active effort to sniff out his interest in MLP.

Why would he make Fluttershy do that? :'(

Uh oh. The only way to solve this is to burn him.. You've got a brony on your hands...

Don't try to understand other people's sexual fetishes, it won't work. But I assume the attraction is similar to that of Hentai, where a person becomes so enamoured with this non-existent character that they find them sexually appealling. Whilst personally I don't understand the appeal of MLP in that fashion, many others may not understand any fetish you may have e.g. feet, WAM, furries etc

So your son likes horses and to role play

Clopper!! XP

Things that matter: how old is he? Simple Anthro or full on? Otherwise... Why do you look through his sexual role plays? O.o

I seem to see a lot of MLB fans on the Internet in a REALLY fast way...even though some are jut trolls :/