I'm not 100% sure what you said, but I think you implied you were confused why Frisk was creepy and why Chara wasn't? Look, if that's the case, this is a swap timeline. That means that the personalities and their place in the story of two opposite characters swap around. In this timeline, Frisk was the first fallen human, and Frisk did everything Chara did in the original timeline, while here, Chara was the last human to fall, and does everything Frisk would do in the original timeline. Idk why you didn't bring up Sans and Papyrus, as you seemed confused with Frisk and Chara. Maybe Frisk and Chara were too much to notice that you didn't think twice about the skellies? Maybe. Whatever. Doesn't matter.