People often have expectations about another person that influence how they act toward that person. such expectations in turn cause that person to behave consistently with the original expectations. the phenomenon is known as

The phenomenon is known as "self-fulfilling prophecy".

Explanation:

Sometimes it happened that you make any prophecy and then it comes true, thus we define self-fulfilling prophecy as a belief you hold about any future event and that comes true. There must be two people involved in self-fulfilling prophecies because you alone cannot have self-fulfilling prophecy.