Lack of Emotions
Not only do they lack emotions such as love and attachment, they have little regard for the feelings of others around them. Being prone to serious mood swings, they can easily be callous, rude, and snap angrily at anyone with no regard for the opposite person's feelings. Moreover, they don't even feel sorry for such behavior. They feel no gratitude for any favors done for them, neither do they thank others for their kindness under any circumstance.