Complex sentence: He is portrayed as a student at the high school that Conner and M'gann attend and him and Conner are shown to be at odds with each other, "facing him down" (as Marvin puts it) before class starts.
Split into simpler sentences: He is portrayed as a student at the high school that Conner and M'gann attend. He and Conner are shown to be at odds with each other, "facing him down" (as Marvin puts it) before class starts.