Nightmare Moon is the evil counterpart of Princess Luna. In this, her Personality is opposite to Princess Luna. Nightmare Moon is evil, loud, impolite and Tricky. She is very impatient and rude. (Sorry)
If someone so much as lays a hand on the guy/girl you love, you will go mad with jealousy. You strive to protect your crush/lover and will eliminate those who come close to them, and I literally mean: ELIMINATE. At first you seem sweet and innocent but you soon turn into an obsessive stalker-ish person.