John heavily impacted the first two seasons before he went missing, but made a return after his son, Dean was on the verge of death. Having stepped in to save his eldest, John later went missing and eventually returned in spirit to help his sons defeat the Yellow-Eyed Demon. However, it was this departure that prompted John's return, years later.
"Our guys are put in a position where they essentially can have a wish granted," Andrew Dabb — producer of Supernatural — said to Entertainment Weekly. "They're actually expecting something else, but [John's return] comes from a place of want by Dean. The need for closure is really want brings John back into their lives."
John's return also prompted the return of another big character, Zachariah (played by Kurt Fuller) who is an angel that doesn't have much of a healthy relationship with Sam and Dean.
"The relationship between these three men were so open, so if I was going to come back, it would be nice to have some closure especially with Sammy," Morgan said.
"The episode gives Sam a chance to forgive," Padalecki added.
A lot has changed on set since Morgan was last there. It wouldn't be a far stretch to guess that the vibe on set has eased up considering the first three seasons were the toughest for creator, Eric Kripke.
"Bob singer and I were fighting for the show's survival at the end of the first three seasons," Kripke said. "We'd have a meeting with the network that we informally called the 'explain-why-we-should-give-you-another-season' meeting."
That's when everyone involved started thinking outside of the box, with Kripke adding that there weren't a lot of genre shows on the network at the time.
"It was mostly Gossip Girl and 90210. We were always like the goth kid at the back of the class that no one really wanted to pay attention to," he said. "So on this little weird horror show, we really got to push some boundaries that hadn't been attempted in TV. There was no one saying, 'That's too crazy.'"0comments
Supernatural's pilot episode aired in 2005, squeezing in just before the merger in 2006 of WB-UPN, which is now The CW.
You can watch Morgan make his comeback on the newest episode titled "Lebanon," airing Thursday Feb. 7 on The CW.