Cosmo

Cosmo is the Cosmos Fiend, and was one of Quanxi's girlfriends. Cosmo has short shoulder-length hair that's fashioned into pigtails. She also has hearts for pupils and the right part of her head is missing, making her brain visible with some of it hanging in front of her. On the surface, Cosmo doesn't exhibit many emotions aside from her usual smiling , seemingly happy-go-lucky attitude. She doesn't speak except for repeating the word "Halloween" and, like the rest of Quanxi's fiends, follows Quanxi around and seems to be in love with her and under her command. When Cosmo uses her powers on Master, another version of herself appears during their conversation, which probably happened in Master's or her mind, hinting that that's her true personality. While she retains her happy demeanor, she is shown to be calmer and able to talk normally, conversing with Master about what's happening. Her surface personality might be the result of her powers affecting herself, causing her to repeat and not be able to think about anything but "Halloween."