Nightmare is a white and purple skeleton, with a gold crown that has a crescent moon engraved on the front of it. He’s usually very shy, as he was hated and bullied by everyone, unlike Dream, his brother. He’s the guardian of negativity, and Dream is the guardian of positivity. The Tree of Feelings has two sides : the negativity side, and the positivity one. They both have apples. The negativity side have black apples, and the positivity side have yellow ones.