Bad ending: "Never, Never give up."
After D recieves the letter his old proffesor wrote in his log, He rushes off in a moment of confusion and anger. David chases after him and talks to him in the lecture hall. D vents about his anger of not being told to his face about the professors feels about him and he states he doesn't know what to do anymore. In this ending, David tells D to never give up on his dreams just because someone else makes fun of them. D, in a moment of feeling misunderstood and full of rage, stabs David in the chest and he falls to the floor bleeding. Just as D is about to leave the room, The crooked man enters and kills him. As David is continuing to bleed out, he walks over and tells him "It wasn't me. It was you. You killed him, and yourself... David." Then he exits the room and David bleeds out then dies.
In order to get this ending, choose the "You shouldn't give up." option when it comes.