Jacob Winograd is the father of Alma and Becca and former husband of Camila.
He died at Halloween years ago in an accident, together with his research assistant Farnaz, when Alma and Becca were children. After Alma's accident her appears to her in persistent visions, urging her to tap into a mysterious ability that allows her to travel through space and time with the hopes of preventing his untimely death.[1] He was a theoretical physicist researching time travel and is convinced he was killed because someone wanted his research.
After research came out that people with schizophrenia had large ventricles, he theorized that mystics, priestesses and shamans might have large ventricles as well, and that their abilities come from a specific brain structure. The few holy people he managed to get their brains scanned confirmed this. He then tried to replicate their abilities by using some of their ancient techniques on students who had larger ventricles[2]. When he found out that Alma had large ventricles as well, he began to experiment on her. At first claiming it was purely to help her unlocking her abilities, he later confesses he was trying to save his mother Geraldine, who had lost her way back to reality. Jacob hoped researching Alma's abilities might enable him to travel back in time and help Geraldine find her way back[3].
Jacob doesn't remember the last hours of his life and when Alma manages to go back she finds out Jacob has been wrong all the time. As it turned out, Camila broke into his lab that Halloween night, searching for Alma. Confronting Jacob with what he had done, she told him to never come home again. When Farnaz learned that Camila didn't know about their experiments, she told him they had gone too far and that she would report him. Jacob managed to momentarily talk her down, but was convinced he would lose everything now - not only his family but also his research and job. Driving Farnaz home, he drove into a ravine, making the accident a murder-suicide by his hands[4].
When he realizes what he has done, he tells Alma to forget about him, but she is convinced it isn't too late for him and that he deserves to live. He possesses his past self, not taking the call about the break-in at the lab, instead going trick or treating with young Alma.[5]
In season 2, it's revealed that Jacob and Alma were successful, creating an alternate timeline where Jacob is still alive in the present day. However, Jacob is hesitant to continue time traveling and thus risk falling into the same obsession that had destroyed him in the original timeline. After discovering that her sister has the same powers, at least in this timeline, Alma convinces a reluctant Jacob and Becca to help save Geraldine.
The family discovers that they're descended from a line of mystics going back at least as far as Jacob's grandmother. When Geraldine, whose real name is Ruchel, was a child, her parents were taken and killed by the Nazis which Geraldine blames herself for as she had foreseen it and tried and failed to warn her parents. In a desperate attempt to save her mother, Jacob repeatedly possesses Geraldine's father and then a Nazi officer to try to save his grandparents, failing each time and nearly killing himself with the effort. Alma brings the Geraldine from the mental hospital who stops Jacob and forgives herself, changing the timeline for the better. In this new timeline, Jacob never loses his mother and, with her support, adopts Camila's son Alejandro from a previous relationship. Geraldine, who kept her real name of Ruchel in this timeline, later dies and is celebrated by the family.
However, Jacob later suffers a stroke that leaves him paralyzed on the right side and unable to speak, although Jacob can still communicate via sign language. Alma believes that the stroke was a consequence of the strain that Jacob had put himself under saving his mother and wants to change things again to save him, but Jacob accepts his fate, happy to have saved his mother and unwilling to change that. Jacob later passes away peacefully and appears to Alma as a ghost to say goodbye alongside Geraldine and his grandparents.
Finally able to accept the loss of her father and experiencing visions showing that the original her is going to suffer a depressing fate if she doesn't fix it, Alma returns to the original timeline and reunites with her family there after saying goodbye to Becca.