She Crossed a Line

So I come back to my dorm, and I'm the second one there. My other roommate, M, walks in. Now we don't share the same bedroom. m walks into her bedroom, and her roommate A had completely rearranged it without asking M if it was okay. The reason? A thought M had too much room, which is a lie. What's worse is A's parents helped her. When all 4 of us get together tonight we are giving A a piece of our mind.