This ending is unlocked if Simon spared the life of Carcass and refused to show trust in Doctor Purnell in the asylum. The therapy fails outright and Simon develops a deep hatred for the world around him. He begins to show signs of paranoid schizophrenia (evidenced by his false belief that the world was looking upon him negatively) as well as misanthropy, and falls into a deeply depressive spiral, leading to self-destruction. Believing Sophie, Doctor Purnell and every one who claimed to care about him, to in reality be looking down on him because of his disability, never caring about him all along. Writing the book does not help, and in fact makes Simon's depression even worse. The depressive spiral coupled with his growing levels of misanthropy and anger over both what he sees as his betrayal by Sophie, and his feeling that the doctor had both made his depression worse and was mocking him grew too much for Simon to bear, and his psychotic rage led him to murder both Sophie and Doctor Purnell. Before committing suicide, Simon leaves a very macabre and sinister suicide note in his diary, which expresses his belief that the world was laughing at him because of his disability, explaining in a justifying sense that he was in the right to kill Sophie and Purnell, he even confesses that if it wasn't for his disability that he would have committed worse atrocities and even goes on to attack whoever finds his remains, wishing for whoever found the suicide note to suffer and become haunted from his dead body.
This ending is unlocked if Simon spared the life of Carcass, but trusted Doctor Purnell and gave him the gun he requested. In this ending, Simon shows respect for Purnell and his efforts to help Simon - but ultimately believes it was futile, coming to the resolution that his life means nothing. Simon is unable to move past the pain he feels as a result of Sophie rejecting him, and he possessively murders her out of a selfish act, unwilling to leave her for anyone else to have. Before taking his own life, he leaves a suicide note in his diary, apologizing to Purnell for the result of the therapy, but thanks him overall for actually trying to help him.
This ending is unlocked if Simon killed Carcass, but refused to give Doctor Purnell his gun. This ending is the reverse of ending 2. Although Simon feels pain due to Sophie's rejection of him, and feels extreme guilt because of the damage his slip into depression and psychosis has done to her, he is able to forgive her, and moves past the rejection that he endured from her, even coming to regard her as the only person who truly cared about him. However, Simon never really was able to trust Doctor Purnell, and in the end comes to the conclusion that his treatment, and the book therapy made him worse, stating that all the book therapy did was made him realise how broken he was, and so he murders Doctor Purnell in a fit of self-absorbed revenge. Before taking his own life, Simon leaves a suicide note, pleading with anyone who finds his remains to not show Sophie, showing how much he cared about her in the end.
Arguably the 'good' ending, unlocked by killing Carcass and trusting Doctor Purnell with the gun. In this ending, Simon did not taken the life of Sophie nor Doctor Purnell and does not commit suicide, instead being prevented from doing so by a psychosis-induced hallucination in which Book Simon arrives. The real Simon works his way through another nightmare whilst in his wheelchair and engages his mental counterpart in a running gunfight, before eventually triumphing and shooting his own nightmarish visage to death - showing that his mind longer needs it and that he has finally released the collected stress of his trauma.
The psychosis ends and it is revealed that Simon did not really shoot his twisted self - but rather two police officers who were entering his apartment. Doctors testify in court that Simon was having a psychosis, and although he feels great guilt for killing the officers, he is committed to a mental hospital for what is most likely the rest of his life. Doctor Purnell continues to act as Simon's counsellor and mentor, a service he is grateful for. Sophie regularly visits Simon in the hospital when she is allowed (the doctors saying that her visits are "destabilising" for him), and although Simon makes note of the fact that she has found a new male friend, he wishes her nothing but the best. Simon even gives himself a happy ending in the book, which represents him coming to terms with his depression and allowing himself to start being treated.
Waking from the brute collision of the vehicle, Simon wakes up pinned to a wall with a man blaming his state of high (on drugs) being the reason of the crash. The man is then revealed to be none other than David Leatherhoff, the protagonist of Afraid of Monsters. Taking in the issue, Simon expresses anger towards David, uttering "What the [HECK]? You...?" in a memorial way, intending that Simon knows David. Simon then threatens David, saying he'll "regret this", which provokes David to run away from the scene. This ending can be achieved if the player mails the "Secret Package" to the mailbox located by the college.
It is notorious that David appears exactly as he appears in Afraid of Monsters, his model not being redesigned nor being a new model (which resembles Silent Hill 2 UFO Ending in which Harry Mason appeared before James Sunderland exactly as he appeared in the first game). Also, despite the fact that he apologises to Simon and talks to him, his voice is never heard. It is most likely that the ending is a joke because of the tone and the file names.