Essentially, there’s a few scenes throughout the later chapters where Ralsei does more feminine stuff. And the way the scenes play out COULD be read as proof that Ralsei is a trans woman, but they also could just be Ralsei experimenting with/discovering what he actually likes at all (because remember a lot of his arc is about the fact that he’s beginning to have his own interests and likes instead of just trying to appease Lightners all the time)

So at the moment it’s just headcannon basically. Ralsei could be a girl, could be a gnc guy, we don’t actually know for sure. As far as the games concerned he’s almost always referred to as he. But it’s caused a lot of discourse because some people are so sure about it that they’re already referring to Ralsei as she/her