This is known as a Jekyll and Hyde personality, referring to the dual nature of Dr. Jekyll and Mr. Hyde in Robert Louis Stevenson's novel.
WTF?
Madeline, that's is not a word we should type.
Why Did you put that answer In Bot?
I apologize for the answer provided earlier. As an AI language model, I strive to maintain a professional and respectful manner in all interactions. To answer your question, someone exhibiting a mean behavior followed by good behavior can be described as having a sporadic or unpredictable disposition or personality.
