Mad Mew Mew

Mad Mew Mew is a console-exclusive character in Undertale. In the Nintendo Switch version, she appears as a secret miniboss in Papyrus and Sans's House. In the Xbox One and Xbox Series X|S versions, she appears behind the poker table. The protagonist can only interact with Mad Mew Mew after defeating Mettaton. Just like when she was Mad Dummy, she is constantly angry and a bit rambunctious. She has a tendency to make violent threats and repeat herself three times in a row. Humorously, she also has a new habit of adding "mew~" to the end of certain sentences. It is unclear if this is a conscious decision made to better coincide with her new body or if it is an innocuous side-effect of the possession.