Answer: Self-fulfilling prophecy
Explanation:
Self fulfilling prophecy is defined as the theory in which exception of any person about another party or person will lead that person or party to behave in a way/manner that the exceptions are confirmed through it.This prophecy is proved or fulfilled through exception.
According to the situation mentioned in question,Alec's expectation that certain group member are hostile is proved by the extraction of coldness from those people which proved their hostility. Thus, the scenario is based on self fulfilling prophecy.