In the popular TV series “Breaking Bad,” Jesse Pinkman, played by Aaron Paul, eventually learns that Walter White, played by Bryan Cranston, was responsible for poisoning Brock Cantillo, the young son of Jesse’s girlfriend, Andrea. However, this revelation comes much later in the series and is a turning point in their tumultuous relationship. Here’s a detailed explanation:

In the fourth season of “Breaking Bad,” Walter White orchestrates a complex plan to poison Brock, a young boy who is the son of Jesse Pinkman’s girlfriend, Andrea Cantillo. Walter uses a poisonous plant called Lily of the Valley to make Brock critically ill, which manipulates Jesse into turning against his former partner, Gus Fring, whom Walter wants to eliminate.
Jesse is devastated by Brock’s illness and believes that Gus, the local drug kingpin, is responsible for the poisoning. Jesse becomes increasingly paranoid and angry, and his relationship with Walter starts to deteriorate. Jesse is determined to take revenge on Gus and becomes more distant from Walter, suspecting that Walter is lying to him about Brock’s poisoning.
However, towards the end of Season 4, Jesse begins to piece together the truth. He realizes that the poison used to make Brock ill is not consistent with the methods Gus typically employs. Jesse becomes suspicious of Walter’s behavior and starts to question Walter’s motives.
In the Season 4 episode titled “End Times,” Jesse confronts Walter and accuses him of poisoning Brock. Walter initially denies it and tries to manipulate Jesse into thinking that Gus is responsible. However, Jesse’s suspicions persist, and he becomes increasingly convinced that Walter is lying to him.
In the following episode, “Face Off,” Jesse discovers evidence that confirms Walter’s guilt. Jesse finds the missing vial of Lily of the Valley in Walter’s home, hidden among his belongings. This is the decisive moment when Jesse realizes that Walter was responsible for poisoning Brock.
Jesse confronts Walter again, and this time, Walter finally admits to poisoning Brock. He justifies his actions by claiming that he did it to protect Jesse and get him on their side against Gus. However, Jesse is devastated and deeply betrayed by Walter’s actions, which resulted in an innocent child being harmed.
This revelation is a major turning point in Jesse and Walter’s relationship. Jesse feels a profound sense of betrayal and anger towards Walter, as he realizes the extent of Walter’s manipulations and lies. This revelation also pushes Jesse to cut ties with Walter and take a different path in his life.
The fallout from the revelation of Walter’s role in poisoning Brock has significant consequences throughout the remainder of the series. It deepens the rift between Jesse and Walter, and Jesse becomes determined to seek justice and break free from Walter’s influence. It sets off a chain of events that impact the storyline and the dynamics between characters in subsequent seasons of “Breaking Bad.”
In conclusion, Jesse eventually finds out that Walter poisoned Brock in “Breaking Bad.” It happens towards the end of Season 4 when Jesse discovers evidence that confirms Walter’s guilt. This revelation is a pivotal moment in the series and has significant consequences for Jesse and Walter’s relationship, leading to further conflicts and developments in the storyline.