WARNING: The following feature contains SPOILERS for Doom Patrol, season 1, episode 14, "Penultimate Patrol."
The penultimate episode of Doom Patrol season 1 (appropriately titled "Penultimate Patrol") took a page from the comics with its twist ending. The final minute of the episode revealed the true villain of the series to be Dr. Niles Caulder, a.k.a. The Chief - the scientist whom saved the lives of all the show's protagonists and took them into his home.
The action of Doom Patrol season 1 focused upon a quintet of misfits who gained superpowers after tragic accidents. When their physician, Dr. Caulder, is abducted by a sinister figure known as Mr. Nobody, the would-be heroes try to seek him out, only to be handily defeated by Mr. Nobody's apparent power to warp time and space. As the season progressed, the team found the resolve to fight back, leading to a confrontation with Mr. Nobody on his home turf and Dr. Caulder confessing that the "accidents" which created them were his truly the end result of his experiments.
The eleventh-hour reveal was a shock, even to those fans of the show who had read the original Doom Patrol comic books, where Dr. Caulder had also secretly engineered the creation of the Doom Patrol. While the show had revealed Dr. Caulder to have something of a checkered past, there had been little in Timothy Dalton's performance to directly suggest The Chief's sinister nature. Yet there were hints throughout the season, leading into "Penultimate Patrol," which suggested that viewers were not being given thslae whole story.
The Grand Reveal
With the aid of the reality-bending bodybuilder known as Flex Mentallo, the team was able to enter into White Space - the void between realities, where Mr. Nobody had vanished with Dr. Caulder. Upon arrival, they found themselves back in their old lives, just before the accidents that forever changed then. Mr. Nobody said they could live out the rest of their lives as they would have been, if they would just agree to forget about Dr. Caulder. Everyone refused to surrender.
Another series of illusions followed, with Mr. Nobody seemingly being defeated and The Chief located before they returned to the real world to become a proper superhero team. A montage ensued, showing the new Doom Patrol dying repeatedly as they faced the same giant robot in battle over and over. It was then that Dr. Caulder relented, realizing the repeating sequence was just another of Mr. Nobody's sick games to weaken his resolve.
Finding themselves back in the White Space, Mr. Nobody said there was no way they could beat him, but that they could be free of him and that Dr. Caulder knew how to arrange it. With a sigh, Dr. Caulder said "The truth will set you free." After some hesitation, Dr. Caulder confessed, as a gleeful Mr. Nobody grinned wickedly - "The tragedies that befell you, they weren't accidents. I was responsible for everything."
How The Twist Was Foreshadowed
Before "Penultimate Patrol," there was nothing in the series to suggest that Dr. Caulder was responsible for engineering the tragedies that created the new Doom Patrol. There were, however, numerous suggestions that The Chief had something of a dark side and was less than loving in regards to his patients. We first see this in the pilot, when The Chief is trying to teach Cliff Steele how to speak again once his brain is implanted in a robot body. Dr. Caulder ignores Cliff's shouting (and the fact that he can speak and curse just fine) when Cliff sees a calendar on the wall and instantly realizes he has lost nearly a decade of his life, quietly turning Cliff's brain off until he is ready to deal with Cliff again.
While this may have only indicated that Dr. Caulder didn't have a great bedside manner, there were other hints that he was far from a saint. The disreputable and drunken wizard Willoughby Kipling said as much in "Cult Patrol," noting that he and Cyborg knew two very different Niles Caulders when Cyborg said that the Dr. Caulder he knew would never kill an innocent child to save the world. Kipling said that the man he had worked with in the past was one "who'll make the decisions that have to be made to keep the world spinning." The puppet show detailing the life of Nazi scientist Von Fuchs in "Puppet Patrol" further revealed that Dr. Caulder was responsible for disrupting the experiment that created Mr. Nobody, establishing a precedent for his creating superpowered people by arranging tragedies.
The biggest hint, however, came early on in "Penultimate Patrol," before the final showdown with Mr. Nobody. Dr. Silas Stone, Cyborg's father, woke up in the hospital and was stunned as Cyborg apologized for having ever thought it possible that his own father would manipulate his memories. Dr. Stone admitted that Victor's suspicions were correct and that not all of his memories were real. Rather than literally coding new memories for him, however, Dr. Stone had gaslighted Victor regarding the events of the night of his accident.
Victor had been led to believe that his mother died in the explosion that he caused during their argument in her lab. In truth, she had survived the explosion and been rushed to STAR Labs along with Victor. Having only enough time and experimental mechanical components to save one of them, Dr. Stone wanted to save his wife. However, he ultimately chose to save his son at the urging of Dr. Niles Caulder, who said that Victor would be a be a better test subject and less likely to reject the cybernetic implants. Again, we see how Dr. Caulder tried to manipulate a tragedy for the sake of an experiment.
How It Happened In The Comics
Dr. Caulder's true nature was originally revealed in Doom Patrol (Vol. 2) #57 in July 1992. It was here that Dr Caulder revealed his full history and how he came to establish the Doom Patrol to a paralyzed Cliff Steele. Steele became frozen in place when Dr. Caulder activated a pre-programmed catchphrase after Cliff had tried to attack Dr. Caulder upon discovering the doctor had shot and killed Joshua "Tempest" Clay, who had come into his secret lab uninvited and seen too much to be allowed to live.
Caulder explained that he had become inspired by Frankstein and, like the famous mad scientist, devoted his studies towards finding the secret of creating life. Along the way he became obsessed with the Catastrophe Theory and the idea that one could plot the sudden emergence of discontinuity in an otherwise stable system. This, coupled with his paralysis at the hands of the villain General Immortus, spurred Dr. Caulder to consider the idea that he might be able to introduce random catastrophes into the lives of various people and remake them into something stronger.
Professional race car driver Cliff Steele, whose body was destroyed in a racing accident, was Dr. Caulder's first test subject/victim. Dr. Caulder considered his experiment with Cliff to be a success, as Cliff developed a sense of compassion and heroism as Robotman that he'd lacked back when he was rich, famous and successful. Caulder arranged similar accidents for actress Rita Farr and test-pilot Larry Trainor, who joined with Steele to form the first incarnation of the Doom Patrol.
It was Dr. Caulder's belief that by transforming people into physical monsters, he could enhance their sense of empathy and make them into heroes, or at least better people. His final plan was to use a quantum computer empowered a series of nanomachines to introduce a catastrophe curve that would alter every person on Earth. Thankfully, Dr. Caulder was killed before he had the chance to enact his plan, ironically being ripped apart by The Candlemaker - a sinister cosmic being whose arrival Joshua Clay had come to warn Dr. Caulder about when Dr. Caulder killed him.
What's Next In The Finale?
Perhaps not surprisingly, given the chaotic nature of the Doom Patrol series so far, it is unclear just where the show is going on from this revelation in the final episode of its first season. The preview trailer is made up entirely of footage from the first 14 episodes and merely urges views to tune in to "Prepare To Meet Their Doom." The episode synopsis on DC Universe says only that the team members will go their separate ways, which makes sense as none of them would be likely to want to stay in Dr. Caulder's manor house after his confession. The only real clue to the story lies in the title, "Ezekiel Patrol," which may be a nod to one of the series' original creations - a doomsday prophet cockroach named Ezekiel, who has been eagerly predicting the fall of humanity since the second episode.