Board Thread:General Discussion/@comment-24100805-20160201152915/@comment-1291765-20180929231334

I feel convinced that Frisk is an effeminate male and Chara is a female tomboy. He has that kind of sleepy, laid-back look that I associate with guys who aren't terribly ambitious. I just can't imagine a girl being quite that... chill or laid back. Chara on the other hand, has this kind of alert, pushy cheerfulness that reminds me of assertive women. I find it hard to picture a guy smiling quite that big to mask their inner state while plotting something destructive.

The gender of other characters in the game really doesn't tell us anything, because they could always be homosexual or bisexual. Papyrus in particular, even if he is male, technically said he wasn't attracted to Frisk at the end of the date... and may have just been too socially awkward to just say "I don't like guys," and thus handled everything the best way he could to avoid being rude, since he did like being appreciated by Frisk and didn't want to lose that.

I believe it's possible that Frisk and Chara actually fight for control of the same soul (he may have even been Chara in a past life, depending on whether we interpret Chara as being inside your head or not). The True Pacifist ending means Frisk wins, resists Chara, and stays true to himself... while in the case of a Genocide Run, that means Chara's will was stronger, and her memories/spirit essentially possessed him slowly over the course of the game, until there was nothing left of him and she was in control. A neutral run means neither of them had full control and so everything remains ambiguous without resolution.