John is the male lead of Crimson Gray, a young man with clinical depression.
John was a good student with an average social life before his depression overwhelmed him. Though his depression occasionally becomes crippling and often prompts feelings of worthlessness, John is usually capable of functioning normally. Perhaps his most notable trait is his extreme open-mindedness, able to feel compassion for Lizzie instead of fearing her.
In a way, John is an inversion of Lizzie. She considers him to be perfect, while he considers himself worthless. Lizzie is extremely competent, while John sometimes can't even do what the player tries to choose.
There are similarities, too, both of them having a mental condition and being focused on other people. John becomes a very supportive partner to Lizzie, trying to understand her pain and help her stabilize. He isn't happy with her utter devotion to him, instead encouraging her to value herself and develop her own interests.
John had a relatively normal childhood, but his parents divorced under unclear circumstances and he lived with his distant father.
Some time after middle school, John's depression emerged in severe form. He began to take medication that was helpful, but unfortunately was used as a test subject for KoiTec's Paxetine, which only suppressed a few symptoms and worsened his condition.
The biggest change in his life was when he met Lizzie in 1990, setting off the events of the game. In the canon path, he accepted her for who she was, actually strengthening her condition in order to save their lives.
The rest of their lives is unknown, though the epilogue an unknown number of years later suggests they lived happily together. Sierra has stated that if a sequel is created, it would take place in 1995 and focus on Lizzie and John after their marriage.