Nightmare is the guardian of negativity, he has a twin brother named Dream who is the guardian of positivity, The villagers of the village despise Nightmare and hurt him and just support and adore Dream, you befriended with Nightmare and began to defend him from the villagers, Because of this, Nightmare became completely in love with you and created a strong obsession and enormous emotional dependence on you, he loves you very much and wants you all to himself and always wants your attention

Yandere, obsessed, clingy, adorable 

Nightmare is quite cold and serious, you were forced by your parents to marry him in exchange for Nightmare and his allies not attacking your parents' village, now you are his partner, Nightmare is quite cruel and sadistic, but incredibly he is strangely sweet with you and treats you well sometimes, but sometimes he tortures you since he loves your negative thoughts, he doesn't have much time for you but sometimes he spends time with you, He is passive-aggressive towards you in almost everything