While Kris, Chara, and Frisk are nonbinary, I have my own headcannons about their other info.
Completely gender neutral voice.
You can't tell they ever had a gender assigned; people just accept that they're an enigma.
Doesn't conform to gender at all, wears the most gender neutral clothing possible.
Frisk isn't their birth name. It's Finkai; no one knows why they hate it, Finkai is a kick ass gender nutural name; they just hate it.
Doesn't like her or him, but won't mind any gender neutral pronouns (They, it, xe, neos, etc)
No one can tell; most people who aren't close with them assume they're male, then see them without a binder and get thrown for a loop. People use they/them to be safe. Kris loves it.
Doesn't conform to gender at all, switches between male and female clothing.
Full name is still just Kris, usually spells their own name as "Kriss" instead for some reason.
Likes men. Will not let you call them gay or straight.
Any you want, they don't really care. Mortal pronouns don't matter to them anymore. When they were alive, they used they/them in the underground, so most people still use they/them.
You can't physically tell at all. They have a completely flat chest, no curves; they get called a beanpole a lot due to their boxy, tall shape.
They dress and act a little more femininely compared to the other two due to their human upbringing being "YOU'RE A GIRL YOU MUST ACT LIKE A GIRL".
Full name is Charlain, Papyrus calls them Charakterny (YES THAT'S A REFERENCE IF YOU KNOW IT).
All three know ballet, Kris is the best at it, though.
If the three were to meet, they would all look at each other and nod in silent understanding.
Kris and Frisk fight about whether or not the soul is evil (Kris hates us, Frisk loves us).
Kris and Chara have a very odd relationship. Chara likes Kris; Kris hates Chara.
Kris will eventually change their legal name to Kriss; nothing changes, they just feel happier.
I just wanted to share my fun lil headcannons as these three mean a lot to me :3
Personal unrelated notes:
Wow, being an afab Kris believer is frustrating when everyone else thinks of Kris as a guy so hard they call THEM by he/him.
I love the whole "Kris loves confusing people." It means so much to me.
I came up with Finkai on the spot.
