I am having a kind of writers block with a short story... not a writers block in a sense, that the problem is, that I just want to challenge myself.
Which methods writers usually use in order to make characters act out of character; and how to build this up quickly (one act in a short story with a three act structure, less than 500 words).
In my specific use case, I want my character, a police officer with pacifistic tendencies, to attack his work mate while having a chat during maintenance of their equipment (very everyday situation).
Which methods will make the use of violence believable in abstract sense, where the work mate must remain very much innocent for his fate; the act of violence is totally undeserved and caused by double meanings only apparent for the main character and the reader.
I have discovered, that using reverse SCARF method would work: Taking away characters Status, Certainty, Autonomy, Relatedness and perception of Fairness; these usually happen in stories before the character snaps. However, I want to go deeper. What other methods are there for me to discover?