What episode does Sam go crazy?
Dean and Sam check themselves into a mental hospital so they can investigate a monster that is attacking patients.
In Season 6, soulless Sam seemed a bit evil, due to his lack of empathy, but was generally referred to as RoboSam. At the beginning of 15.04 Atomic Monsters, Sam has a nightmare where he embraced the demon blood and became the leader of the demon army as Azazel had intended.
Sam does not do much evil after the Kripke-era on his own, mistakes yes, bad things, sure, but not much pure evil like this through his own free will.
The battle that brought him down released hundreds of demons from Hell into an unsuspecting world. And it cost Sam (Jared Padalecki) his life. But a grief-stricken Dean (Jensen Ackles) made a deal with the Crossroad Demon (guest star Sandra McCoy) -- his soul for Sam's resurrection.
Sam's supernatural abilities are the result of him being fed Azazel's demon blood while he was an infant. Sam exhibits signs of precognition throughout the first season, manifesting as dreams of others' deaths and later as visions.
Using holy fire, Sam is able to cure himself and then save the remaining people in the town. Returning to the bunker, he and Dean find Castiel begging for help.
When Dean had first met Ben Dean considered the possibility that Ben might actually be his son. Lisa confirmed to Dean that Ben wasn't his son and his similarities to him was due to her 'type' that she hooked up with that Dean had fallen under.
Azazel aka the Yellow-Eyed Demon (Fredric Lehne) was the thing that killed Sam and Dean's mother; he was the thing that stood over Sam's crib and dripped blood into his mouth, turning him into one of his future soldiers; he was the reason the Devil's Gate opened; and he was the reason, ultimately, that Dean sold his ...
In Like A Virgin, Sam now has his soul back and Dean calls Castiel to check on Sam. Castiel tells Dean that Sam's soul felt like it had been skinned alive. Later on in the episode, Sam awakes and recalls Castiel being killed while Lucifer possessed him but Dean and Bobby tell him he was resurrected, to his relief.
The writers just left it out because they don't want write him with abilities anymore. Sam refused to flip on those switches like Ava and Jake. So he can't turn them on.
Why did Sam let Dean become a vampire?
After Veritas revealed that Sam was lying, even under her power, Sam admitted that he let Dean get turned into a vampire as he knew about the cure and that they could turn Dean back.
Later, when Edgar visits a half-vampire Alan, seeking his help in hunting down the Alpha Vampire, it is revealed that Edgar had in fact killed Sam during the post-credits scene of the previous film (confirming that Sam had become a full fledged vampire, and not a half-vampire).
Sam voluntarily commits herself to a mental institution over her suddenly emerging feelings about Freddie. Sam voluntarily commits herself to a mental institution over her suddenly emerging feelings about Freddie.
5.11: Sam, Interrupted Ghostfacers: A Supernatural Rewatch
In the 93rd episode of Supernatural, Dean and Sam check themselves into a mental hospital so they can investigate a monster that is attacking patients.
iLost My Mind - iCarly (Season 5, Episode 1) | Apple TV. S5 E1: Carly discovers that Sam has checked herself into a mental hospital, thinking she's crazy for liking Freddie.
Sam, off alone, cannot snap himself back into reality. Sam's broken mental state masterfully unfolds. Dean and Bobby find Sam and snap him out of his vivid hallucination of Lucifer. After a very long rest Dean wakes him, cares for his hand, and then asks for the truth.