Walter Bishop (John Noble) is one of the lead characters on the TV show "Fringe". At the start of the show, he has spent several years confined to a mental institution and suffers recurring mental health issues and amnesia. Walter was one of two scientists who conducted secret research for many years into the area of "fringe science". Because of his experience, the FBI required his expertise to help solve a series of weird occurrences and crimes. He is initially freed from the asylum by FBI agent Olivia Dunham (Anna Torv) and released into the care of his son, Peter Bishop (Joshua Jackson) and all three work to solve these cases under the auspices of the "Fringe Division", run by Philip Broyles (Lance Reddick) from Homeland Security.
Most of the storylines in "Fringe" involve the consequences of a series of experiments that were conducted in a laboratory at Harvard, including experiments on children. Walter and William Bell (Leonard Nimoy) used drugs on the children to improve their psychic abilities, the most powerful of whom was later shown to be Olivia. Also featured in a number of storylines is a parallel universe, where things are similar but subtly different, with the possibility of travel and war between the two universes. The third major component of many episodes is the company "Massive Dynamic", which was formed by William Bell based on the results of the research that he had conducted with Walter. William Bell was later shown to be residing in the parallel universe and was unable to travel back for fear of destroying his home world.
As the story progresses, Walter starts to recover from his mental problems which were partially caused by his heavy use of mind-altering drugs (including LSD). There was also an element of guilt after his real son, Peter died of a childhood illness and Walter traveled to the other universe to save the alternate version of his son who was also dying from the same illness. Walter cured Peter and brought him back to this universe to raise as his own. When this secret became known to Peter, he grew angry with Walter and traveled back to his own universe with his "real" father, an alternate version of Walter who was a high-ranking government official. When Walter realized what had happened, he and Olivia went to find Peter, hoping to bring him home. Walter's plan was a success but he was shot in the parallel universe and almost did not make it back. The sacrifice of his old friend and colleague William Bell was instrumental in their escape.
"Know that we had noble goals. We believed that our world needed guardians, protectors. That you children would be those protectors."
"Do you know what you are putting into our bodies? Death, delicious strawberry flavored death."
"When you open your mind to the impossible, sometimes you find the truth."
"Oh, I don't think so. If you were actually going insane, you'd likely have no idea what's happening. Take it from me."