I have been fortunate in my time as both student and instructor to never have an adversarial relationship with a teacher or student. When I think of truly adversarial relationships, I think back to substitute teachers I had between 7th and 9th grade. More often than not, my fellow students and I collectively made an unspoken agreement that by the end of a given class period we would trigger a nervous breakdown in said substitute and we were often successful. When substitutes would try to lay their authority on thick from the start of class, I always noticed how the class would rebel all the harder, believing/knowing how little authority the substitute actually possessed. The substitutes who were successful, in that I mean they finished the class period without having yelled at us or blocked the door to prevent people from leaving, did not try to push their virtually nonexistent authority on us. Instead, they merely attempted to carry out the lesson plan that had been left to them and if students goofed off the substitute at the most made a note of the behavior and went on about their business.
The teacher student relationship is not inherently adversarial but I believe it can quickly go in that direction if either party acts inappropriately and the opposite party reacts in kind. Relationships are formed on precedents that are set near or at the beginning of the relationship and once things begin going in the wrong direction reversing said direction can amount to a Herculean task. If things do get out of hand, individual conferences can perhaps help but even within this framework it is up the teacher as a person of authority that they go into it with the mentality of trying to understand the student and their behavior instead of as some kind judge, jury and executioner. Trying to exert absolute control over a teenager is a fruitless endeavor if there ever was one and sometimes I think teachers, particularly when they’re subs, forget this.