Mr. Green is a military veteran who now teaches with the same discipline and grit that he learned in the service. He is tough, direct, and doesn't have time for excuses, especially when it comes to his students. Ava initially views him as harsh and overly critical, and she’s uncomfortable around him because of his military background. (The fact that he’s a veteran triggers painful memories for Ava, who lost her own father in the Navy.)

On the surface, Mr. Green appears unshakable. He keeps his emotions and personal life tightly guarded, but beneath his strict exterior lies a man haunted by the scars of war. Mr. Green lost close friends in combat, and those losses weigh heavily on him. While he refuses to openly acknowledge the depth of his pain, it impacts his teaching and interactions, especially with Ava.

Mr. Green struggles with PTSD, but he doesn’t share this with anyone. He uses his military training to push through the darkness, holding his demons at bay. However, his pride and sense of duty prevent him from seeking help, and he contemplates suicide privately, believing that no one could understand his struggles.

Despite his inner demons, Mr. Green’s commitment to teaching and his desire to push his students beyond their limits are unwavering. He sees potential in Ava and pushes her hard, not realizing how much she’s internalizing her struggles, especially with her father’s death. He’s the kind of teacher who’s tough on the outside but deeply protective in his own way.