John and Lester couldn't believe that Marcus would sell them out as he confessed to the Guidance Counselor. That move was unexpected of him.
Because of that, they lost their faces against Matthew. The supposed revenge which they plotted against Matthew backfired on them.
The Guidance Counselor scolded them for what they did. They told the Guidance Counselor that everything was just a misunderstanding. They didn't mean to harm Sophia. In the end, they refused to admit their wrongdoings.
However, Matthew insisted that it's not a misunderstanding, not this case. It was all planned by them because he even heard the conversation between Marcus's sister and her friends. They were talking about Sophia and Marcus that night.
After hearing that, the Guidance Counselor was enraged. Who would have thought that they would try to do that evil scheme against Sophia? He told them that he would look deeper into this and investigate further.
