SPOILER WARNING: This article contains major spoilers for "Lebanon," the 300th episode of Supernatural.
At long last, Jeffrey Dean Morgan has returned to Supernatrual as John Winchester. In "Lebanon," the series' 300th episode, a wish gone wrong plucked John from the year 2003 and brought him to 2019.
Despite Dean's ongoing struggle with the archangel Michael, the Winchester brothers have continued to travel the country, taking on supernatural cases. The case that launched "Lebanon" was personal: when their hunter friend was murdered, they tracked his occult items down to Precious Pawn. There, they fought the pawn shop owner, who died in the struggle. On their way out, they gathered all the dangerous supernatural items they could find and took them back to the bunker.
As Sam glimpsed through the pawn shop owner's records, he stumbled across an interesting artifact. "It's one of eight ancient Chinese treasures. It's a pearl that grants wishes, sort of," Sam revealed to Dean. "Well, technically, it's supposed to give you what your heart desires." Together, they decided to use this pearl to get rid of Michael, who is locked away somewhere in Dean's subconscious.
However, the pearl didn't work quite the way they thought it would. Dean took the pearl and concentrated. Instead of banishing Michael, it brought the long-deceased John Winchester to the bunker. After a brief skirmish, they pieced together what happened. John believed the year was 2003, indicating he had traveled through time. When he demanded to know how he had turned up in 2019, Sam said, "I think we summoned you."
John's presence in 2019 led to his emotional reunion with his wife Mary, who was killed by the demon Azazel when Sam and Dean were children. The brothers gave their parents a moment alone and took stock of what happened. "You said that the pearl gives you what your heart desires, right? So my heart desired," Dean pointed out. "I've wanted this, man. I've wanted this since I was four years old."
John's return, of course, was too good to be true. Because he had been pulled from 2003, the timeline began to change. Slowly, everyone in the town forgot who they were. Then a wanted poster for Dean turned up in a shop window, while a TED Talk video of Sam surfaced online. Soon, they were attacked by the angel Zachariah, who never died, and Castiel, who never got to know the Winchester brothers and thus never broke rank with the angels. They realized they would have to send John back, or else these changes would become permanent. Worse, their mother Mary would simply fade away.
John took the news well, even though it meant he would forget what he witnessed in 2019. "I mean, me vs. your mom, that's not even a choice," he said with a sad smile. After they shared dinner together, he bid his family a tearful goodbye. "You two, you take care of each other," he told Sam and Dean. "I am so proud of you boys. I love you both so much." With that, he took Mary's hand. Sam destroyed the pearl, which sent John back to the appropriate time period and set the timeline straight. The episode closed with John waking up in the Impala to a call from Dean, who he told, "I just had one hell of a dream."
Before he left, John provided some much-needed closure for his sons. In a moment alone, he apologized to Sam for not being what he needed and gave Sam a chance to resolve their differences and say a proper goodbye. He also told Dean he was proud of the man he had become.
By returning to 2003, John sealed his face. He would go on to sacrifice his life to save Dean in the Season 2 premiere. Prior to "Lebanon," Morgan last appeared on the series in a brief cameo during "All Hell Breaks Loose: Part 2," the Season 2 finale, which aired over a decade ago.
Airing Thursdays at 8 pm ET/PT on The CW, Supernatural stars Jensen Ackles, Jared Padalecki, Misha Collins and Alexander Calvert.