What Dreams May Come

While vacationing in Switzerland, pediatrician Chris Nielsen (Robin Williams) meets artist Annie Collins (Annabella Sciorra). They are attracted to each other, and bond as if they had known each other for a long time. They marry and have two children, Ian (Josh Paddock) and Marie (Jessica Brooks Grant). Their idyllic life ends when the children die in a car crash. Life becomes difficult: Annie suffers a mental breakdown and the couple contemplates divorce, but they manage through their losses.
On the anniversary of the day they decided not to divorce, Chris is killed in another car crash. Unaware that he is dead, and confused that no one will interact with him, Chris lingers on Earth. He sees Annie's attempts to cope with his loss and attempts to communicate with her, despite advice from a presence that this will only cause her more pain. When his attempts cause more sorrow, he decides to move on.
Chris awakens in Heaven, and learns that his immediate surroundings can be controlled by his imagination. He meets a man (Cuba Gooding, Jr.) he recognizes as Albert, his friend and mentor from his medical residency, and the presence from his time as a "ghost" on Earth. Albert will guide and help in this new afterlife. Albert teaches Chris about his existence in Heaven, and how to shape his little corner, and to travel to others' "dreams". They are surprised when a Blue Jacaranda tree appears unbidden in Chris' surroundings, matching a tree in a new painting by Annie, inspired by Annie's belief that she can communicate with Chris in the afterlife. Albert explains that this is a sign that the couple are truly soul mates. Annie decides that Chris cannot "see" the painting, however, and destroys it. At the same time, Chris sees his version of the tree disintegrate before his eyes.
Chris laments that he can no longer see his wife and soon encounters a woman who he comes to recognize as his daughter Marie, living in an area resembling a diorama that she loved in her lifetime. The two share a tearful reunion.
Meanwhile, Annie is unable to cope with the loss of her husband and decides to commit suicide. Chris, who is initially relieved that her suffering is done, grows angry when he learns that those who commit suicide go to Hell; this is not the result of a judgment made against them, but rather their own tendency to create "nightmare" afterlife worlds based on their pain. Chris is adamant that he will rescue Annie from Hell, despite Albert's insistence that no one has ever succeeded in doing so with a suicide. Albert agrees to find Chris a "tracker" to help search for Annie's soul.
On the journey to Hell, Chris recalls his son, Ian. Remembering how he'd called him the one man he'd want at his side to brave Hell, Chris realizes that Albert is truly Ian. Ian explains that he chose Albert's appearance because he knew that Chris would listen to Albert without reservation. Before they part, Ian begs Chris to remember how he saved his marriage following Ian and Marie's deaths. Chris then journeys onward with the tracker.
Chris must walk across the field of Faces of the Damned, stepping on their faces as he navigates across it. The damned can be heard talking, including a businesswoman who says she never over-billed her clients. Chris and the tracker arrive at a dark and twisted version of Chris and Annie's house. The tracker then reveals himself as the real Albert and warns Chris that if he stays with Annie for more than a few minutes he may be permanently trapped in Hell, advising that all Chris can reasonably expect is an opportunity for a final farewell to Annie.
Chris enters their now-horrific looking home to find Annie suffering from amnesia, unable to remember her suicide, and visibly tortured by her decrepit surroundings. Unable to stir her memories, the tracker sees Chris give up his quest to save Annie from hell. But instead of returning to Heaven, Chris chooses to join Annie forever in Hell. As he declares to Annie his intent to stay, his words parallel something he'd said to her as he left her in an institution following the children's deaths, and she regains her memories while Chris is making her nightmare his. Annie, wanting nothing more than to save Chris, ascends to Heaven, bringing Chris with her.
Chris and Annie are reunited with their children in Heaven, and all appearances are restored. Chris proposes reincarnation, so he and Annie can experience life together again. The film ends with Chris and Annie meeting again as young children in a situation that parallels their first meeting.

Question: What controls Chris's environment?
Answer: His imaginations