To dream of anal sex symbolizes the creation of problems or negative experiences. Life experiences that totally "screw you over", and leave you with unresolved problems. It reflects choices that never lead to anything productive.
Anal sex in a dream is a sign that a situation is being made worse or that you feel you are getting "the shaft" from someone. Anal sex may also be a sign that you are giving in to bad habits.
To dream of anal rape symbolizes a sense of powerlessness to stop a problem from "screwing you over." You may that problems are being made for you or that they are too big to overcome.
Example: A man dreamed of his father having anal sex with him. In real life he had a moral dilemma that poor choices were exacerbating. His father having anal sex with him reflected a bad conscience making the problem worse.
Example 2: A man dreamed of a demon anally raping another man. In real life this man was experiencing his business being totally destroyed and felt powerless to stop it. The demon rape reflected his perception of horrible and unfair it felt to witness his business going under.