She never stopped smiling for no reason
Anyway I wonder why Dess is characterized as being a childhood friend of Asriel, having an association with red heart-like objects, being messy, rebellious, impulsive, and hard-to-pin-down as a person, and having vanished one day. And have it be that no one in the story's current day talks about her disappearance directly, while it simultaneously being the case that her having done so was the inciting incident that kicked off the entire plot.
Furthermore, I wonder why, were Dess to be the Knight, whose weapon being the Black Knife, who notably attacks with gigantic red slashes that appear to tear the fabric of reality apart, thus making her associated heavily with knives -- which she factually is, given by the combat knife she kept in her room, perhaps tying it the knife that Kris may or may not have inherited from her.
I wonder why she would have a green shirt with a yellow stripe in her closet, like some sort of Important Person's Shirt. I wonder!
...
I wonder why, during the Undertale 10th Anniversary Livestream, Asriel's lines when he was calling out to Chara had them edited to state that he specifically didn't "want to keep growing up without" them?
Who could say!