Corly is a Mobian child around the same size as the protagonist, a bit older than Rlop, having the same height as them. They have black hair, black eyes and rosy blushing cheeks. They wear an unzipped Light blue hoodie over a white t-shirt. They wear black pants, blue gloves and boots. When Chara uses magic their eyes become glowing green.
Contrary to the common depiction of their Fandomtale counterpart, Corly does not feel any hatred. Actually, they care a lot about monsters in Underground, especially their family, which they consider to be the coolest.
They like to tease Rlop, who Corly calls "pretty mirror" due to their physical resemblance, and Jamie, calling him KayKay, saying often that he's cute and that they are cooler than them, even though Corly considers Jamie the coolest monster in the Underground.
Despite their teasing nature, Corly can be easily offended, for example when Rlop says that Jamie is cooler than them. Corly also has a serious side, they are conscious that monsters are delicate and are determined to save them.
They go to Grillby's a lot, petting the dog squad and they like White chocolate quite a lot. They also like to prank people with ketchup.
Corly plays a supporting role in Fandomshift. They are very happy when they meet Rlop, starting to follow them in their journey to Snowdin, giving them advice and teasing them. Corly refers to them as "pretty mirror" or "partner".
Jamie is Corly's adoptive brother. They love Jamie a lot, caring about him and protecting him when it is needed. They consider him the cutest and coolest monster in the Underground, and they do not want that any harm is done toward him, as shown when they are worried about Rlop's behaviour.
Corly hasn't met TUTF355 face-to-face, but has spoken to him. One night, Corly grabbed their vine-cutting knife and ran from home, going all the way to the door of the Ruins. It is highly implied that Corly was fixing to commit suicide, when TUTF355' voice came from the other side of the door. They answered almost on reflex, and spent the next several hours talking, with Corly answering TUTF355' questions as best as possible. On the topic of families, Chara talked about theirs, and (presumably) how he wasn't sure if their kindness was real or a cruel joke; TUTF355 mentioned he hadn't seen his "in centuries." By the time they had finished, Corly had come to realize the kindness and trust shown by the monsters trapped in the Underworld was completely legitimate, and Corly had abandoned their previous idea and ran home; the first thing they did was cling to Jamie and bawl their eyes out.