As Saul goes to grab his gun, Jesse reaches it first and points it at the bloodied lawyer. He wants him to admit that he stole the ricin cigarette to help Walt. Saul pleads with Jesse.
Looking at the cigarette pack and thinking about the missing weed, Jesse has an epiphany. Jesse thinks back to the action of Episode 412 and 413 , when he thought that his girlfriend Andrea's young son Brock was poisoned by the Ricin cigarette that Walt had made and gave Jesse to poison Gus Fring.
I have no problem with this part, I can see why he'd make the connection. The thing is, Walt already gave him an explanation for what happened to the ricin cigarette. At Jesse's house, Walt planted the fake one in the Roomba, then pretended to discover it and showed it to Jesse before disposing of it.
He didn't have the ricin cigarette in his packet anymore and he immediately suspected that to be the cause of Brock's sickness.
Jesse finally realizes that there's a great evil in his life and that he can't begin any sort of new life until he wipes that cancer out. As he spills the gasoline all over the home of the man he still calls Mr. White, Jesse finally takes the fight to the man who's pushed him to this breaking point.
He is sentenced to 86 years in prison, where he is revered by fellow inmates who recognize him as Saul. Kim visits him and they share a cigarette. As she departs, he goes to the prison yard to see her off and "shoots" her finger guns. Kim acknowledges the gesture and leaves.
Despite plans to kill off the character at the end of the first season, Paul's performance convinced the showrunner and head writer Vince Gilligan to keep Jesse in the show. The character and Paul's performance have received acclaim from critics and fans.
Saul definitely knows that Walt poisoned Brock. In 501 "Live Free Or Die," Saul tries to end his business relationship with Walt, noting that he didn't know the kid (Brock) was gonna end up in the hospital.
Jesse eventually comes to the realization that Walt's imperative to cook the entire barrel before the methylamine became denatured was a ruse to build their inventory, and that the methylamine would not spoil.
Jesse gets some flypaper which they hang around the lab, as well as some sleeping pills that he secretly puts into Walt's coffee.
In the next episode Jesse tells Walt that he things Mike is dead and mentions that “walt would have to look over his shoulder if Mike was alive…” this dialogue is referring back to the shot over Walt's shoulder. that's how Jesse knows.
Yes Jesse found out that Walt stole the ricin right at the time of brocks poisoning but it wasn't ricin that poisoned him....
But he also knew that the risk of Brock dying was real, especially if he was not diagnosed in time. Moreover, it is Jesse who immediately directs the doctors towards a poisoning. Perhaps without this, the diagnosis would have been too late.
At the time, Jesse blamed himself for losing the cigarette. At last, he realizes that Huell stole it to give to Walt, on Saul's orders. Jesse concludes that Walt poisoned Brock and storms back to extract a gunpoint confession from Saul. Jesse is out for revenge.
The audience never learns the contents of Jesse's letter to Brock, though it's implied that it's an attempt at explaining/apologizing/making amends for all the evil that Jesse unwillingly brought into Brock's life.
The chemistry in the show is basically accurate and is described in quite some detail. At first, Walter pursues a synthetic method starting from pseudoephedrine, a substance that can be extracted from some commercial cold remedies.
It's got a secret ingredient. Jesse Pinkman : [about to try it] What secret ingredient? Jesse Pinkman : Chili powder. Tuco Salamanca : [wiping his hand clean and tossing the baggie away] I hate chili powder.
In one scene, in their makeshift mobile meth lab out in the desert, Walt is being threatened by two gangsters. He improvises a method to gas them by throwing red phosphorus into hot water. Walt manages to run out, locking the gangsters in. He later explains to Jesse that this reaction produced poisonous phosphine gas.
Firstly, Walt really wants to steal the ricin from Jesse in the fifth season. Why ? Jesse was ready to disappear with the misterious guy. It appears that the fat black guy stole the pack with the ricin cigarette in it and his pot.
Gus would poison Brock for the same reason that Walt did poison Brock: To force Jesse to act and shore up his loyalty. This whole plot device works brilliantly for that reason alone. [Person A] poisons Brock so that Jesse distrusts [Person B] and becomes more loyal to [Person A]. A could be Gus.
Later on, Walt himself admitted to Jesse that he poisoned Brock with a Lily of the Valley plant just to keep Jesse on his side in order for them to orchestrate the death of Gus Fring, but by that point, their relationship was already in shambles.
The finale did give Jesse a happy ending of sorts when Walt, finally showing something like remorse for what he'd done to his former student, set him free.
Jesse shows his love for Walt through simple, often under-noticed deeds. Giving him a birthday present when nobody else cared to. Apologizing for threatening his life even when both the characters and the audience know, deep down, that Walter is deserving of death.
Walt pleads to Jack to spare Hank's life, offering his entire fortune to Jack. Hank refuses to beg for his life and asks Walt how such an intelligent man could be too naive to see that Jack had already made his decision. Hank then tells Jack to do what he has to do and Jack kills him with a shot to the head.