You’re (Female) Frisk

Chara Sits in the room You, Asriel, And him share, Asriel is out, along with toriel and asgore, and Chara just sits there, polishing his knives he collects

“So, Frisk, why are you in here…?”

He’s acting arrogant, like it’s his room, when you and asriel share it with him, he’s either trying to toy with you or some weird way of “asserting dominance” over you